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=encoding utf8

=head1 NAME

perlebcdic - Considerations for running Perl on EBCDIC platforms

=head1 DESCRIPTION

An exploration of some of the issues facing Perl programmers
on EBCDIC based computers.  We do not cover localization, 
internationalization, or multi-byte character set issues other
than some discussion of UTF-8 and UTF-EBCDIC.

Portions that are still incomplete are marked with XXX.

Perl used to work on EBCDIC machines, but there are now areas of the code where
it doesn't.  If you want to use Perl on an EBCDIC machine, please let us know
by sending mail to perlbug@perl.org

=head1 COMMON CHARACTER CODE SETS

=head2 ASCII

The American Standard Code for Information Interchange (ASCII or US-ASCII) is a
set of
integers running from 0 to 127 (decimal) that imply character 
interpretation by the display and other systems of computers.  
The range 0..127 can be covered by setting the bits in a 7-bit binary 
digit, hence the set is sometimes referred to as "7-bit ASCII".  
ASCII was described by the American National Standards Institute 
document ANSI X3.4-1986.  It was also described by ISO 646:1991 
(with localization for currency symbols).  The full ASCII set is 
given in the table below as the first 128 elements.  Languages that 
can be written adequately with the characters in ASCII include 
English, Hawaiian, Indonesian, Swahili and some Native American 
languages.

There are many character sets that extend the range of integers
from 0..2**7-1 up to 2**8-1, or 8 bit bytes (octets if you prefer).
One common one is the ISO 8859-1 character set.

=head2 ISO 8859

The ISO 8859-$n are a collection of character code sets from the 
International Organization for Standardization (ISO) each of which 
adds characters to the ASCII set that are typically found in European 
languages many of which are based on the Roman, or Latin, alphabet.

=head2 Latin 1 (ISO 8859-1)

A particular 8-bit extension to ASCII that includes grave and acute 
accented Latin characters.  Languages that can employ ISO 8859-1 
include all the languages covered by ASCII as well as Afrikaans, 
Albanian, Basque, Catalan, Danish, Faroese, Finnish, Norwegian, 
Portuguese, Spanish, and Swedish.  Dutch is covered albeit without 
the ij ligature.  French is covered too but without the oe ligature. 
German can use ISO 8859-1 but must do so without German-style
quotation marks.  This set is based on Western European extensions 
to ASCII and is commonly encountered in world wide web work.
In IBM character code set identification terminology ISO 8859-1 is
also known as CCSID 819 (or sometimes 0819 or even 00819).

=head2 EBCDIC

The Extended Binary Coded Decimal Interchange Code refers to a 
large collection of single- and multi-byte coded character sets that are
different from ASCII or ISO 8859-1 and are all slightly different from each
other; they typically run on host computers.  The EBCDIC encodings derive from
8-bit byte extensions of Hollerith punched card encodings.  The layout on the
cards was such that high bits were set for the upper and lower case alphabet
characters [a-z] and [A-Z], but there were gaps within each Latin alphabet
range.

Some IBM EBCDIC character sets may be known by character code set 
identification numbers (CCSID numbers) or code page numbers.

Perl can be compiled on platforms that run any of three commonly used EBCDIC
character sets, listed below.

=head2 The 13 variant characters

Among IBM EBCDIC character code sets there are 13 characters that
are often mapped to different integer values.  Those characters
are known as the 13 "variant" characters and are:

\ [ ] { } ^ ~ ! # | $ @ `

When Perl is compiled for a platform, it looks at some of these characters to
guess which EBCDIC character set the platform uses, and adapts itself
accordingly to that platform.  If the platform uses a character set that is not
one of the three Perl knows about, Perl will either fail to compile, or
mistakenly and silently choose one of the three.
They are:

=head2 0037

Character code set ID 0037 is a mapping of the ASCII plus Latin-1 
characters (i.e. ISO 8859-1) to an EBCDIC set.  0037 is used 
in North American English locales on the OS/400 operating system 
that runs on AS/400 computers.  CCSID 0037 differs from ISO 8859-1 
in 237 places, in other words they agree on only 19 code point values.

=head2 1047

Character code set ID 1047 is also a mapping of the ASCII plus 
Latin-1 characters (i.e. ISO 8859-1) to an EBCDIC set.  1047 is 
used under Unix System Services for OS/390 or z/OS, and OpenEdition 
for VM/ESA.  CCSID 1047 differs from CCSID 0037 in eight places.

=head2 POSIX-BC

The EBCDIC code page in use on Siemens' BS2000 system is distinct from
1047 and 0037.  It is identified below as the POSIX-BC set.

=head2 Unicode code points versus EBCDIC code points

In Unicode terminology a I<code point> is the number assigned to a
character: for example, in EBCDIC the character "A" is usually assigned
the number 193. In Unicode the character "A" is assigned the number 65.
This causes a problem with the semantics of the pack/unpack "U", which
are supposed to pack Unicode code points to characters and back to numbers.
The problem is: which code points to use for code points less than 256?
(for 256 and over there's no problem: Unicode code points are used)
In EBCDIC, for the low 256 the EBCDIC code points are used. This
means that the equivalences

pack("U", ord($character)) eq $character
    unpack("U", $character) == ord $character

will hold. (If Unicode code points were applied consistently over
all the possible code points, pack("U",ord("A")) would in EBCDIC
equal I<A with acute> or chr(101), and unpack("U", "A") would equal
65, or I<non-breaking space>, not 193, or ord "A".)

=head2 Remaining Perl Unicode problems in EBCDIC

=over 4

=item *

Many of the remaining problems seem to be related to case-insensitive matching

=item *

The extensions Unicode::Collate and Unicode::Normalized are not
supported under EBCDIC, likewise for the encoding pragma.

=back

=head2 Unicode and UTF

UTF stands for C<Unicode Transformation Format>.
UTF-8 is an encoding of Unicode into a sequence of 8-bit byte chunks, based on
ASCII and Latin-1.
The length of a sequence required to represent a Unicode code point
depends on the ordinal number of that code point,
with larger numbers requiring more bytes.
UTF-EBCDIC is like UTF-8, but based on EBCDIC.

You may see the term C<invariant> character or code point.
This simply means that the character has the same numeric
value when encoded as when not.
(Note that this is a very different concept from L</The 13 variant characters>
mentioned above.)
For example, the ordinal value of 'A' is 193 in most EBCDIC code pages,
and also is 193 when encoded in UTF-EBCDIC.
All variant code points occupy at least two bytes when encoded.
In UTF-8, the code points corresponding to the lowest 128
ordinal numbers (0 - 127: the ASCII characters) are invariant.
In UTF-EBCDIC, there are 160 invariant characters.
(If you care, the EBCDIC invariants are those characters
which have ASCII equivalents, plus those that correspond to
the C1 controls (80..9f on ASCII platforms).)

A string encoded in UTF-EBCDIC may be longer (but never shorter) than
one encoded in UTF-8.

=head2 Using Encode

Starting from Perl 5.8 you can use the standard new module Encode
to translate from EBCDIC to Latin-1 code points.
Encode knows about more EBCDIC character sets than Perl can currently
be compiled to run on.

use Encode 'from_to';

my %ebcdic = ( 176 => 'cp37', 95 => 'cp1047', 106 => 'posix-bc' );

# $a is in EBCDIC code points
   from_to($a, $ebcdic{ord '^'}, 'latin1');
   # $a is ISO 8859-1 code points

and from Latin-1 code points to EBCDIC code points

use Encode 'from_to';

my %ebcdic = ( 176 => 'cp37', 95 => 'cp1047', 106 => 'posix-bc' );

# $a is ISO 8859-1 code points
   from_to($a, 'latin1', $ebcdic{ord '^'});
   # $a is in EBCDIC code points

For doing I/O it is suggested that you use the autotranslating features
of PerlIO, see L<perluniintro>.

Since version 5.8 Perl uses the new PerlIO I/O library.  This enables
you to use different encodings per IO channel.  For example you may use

use Encode;
    open($f, ">:encoding(ascii)", "test.ascii");
    print $f "Hello World!\n";
    open($f, ">:encoding(cp37)", "test.ebcdic");
    print $f "Hello World!\n";
    open($f, ">:encoding(latin1)", "test.latin1");
    print $f "Hello World!\n";
    open($f, ">:encoding(utf8)", "test.utf8");
    print $f "Hello World!\n";

to get four files containing "Hello World!\n" in ASCII, CP 0037 EBCDIC,
ISO 8859-1 (Latin-1) (in this example identical to ASCII since only ASCII
characters were printed), and 
UTF-EBCDIC (in this example identical to normal EBCDIC since only characters
that don't differ between EBCDIC and UTF-EBCDIC were printed).  See the
documentation of Encode::PerlIO for details.

As the PerlIO layer uses raw IO (bytes) internally, all this totally
ignores things like the type of your filesystem (ASCII or EBCDIC).

=head1 SINGLE OCTET TABLES

The following tables list the ASCII and Latin 1 ordered sets including
the subsets: C0 controls (0..31), ASCII graphics (32..7e), delete (7f),
C1 controls (80..9f), and Latin-1 (a.k.a. ISO 8859-1) (a0..ff). In the 
table non-printing control character names as well as the Latin 1 
extensions to ASCII have been labelled with character names roughly 
corresponding to I<The Unicode Standard, Version 3.0> albeit with 
substitutions such as s/LATIN// and s/VULGAR// in all cases, 
s/CAPITAL LETTER// in some cases, and s/SMALL LETTER ([A-Z])/\l$1/ 
in some other cases. The "names" of the controls listed here are 
the Unicode Version 1 names, except for the few that don't have names, in which
case the names in the Wikipedia article were used
(L<http://en.wikipedia.org/wiki/C0_and_C1_control_codes>).
The differences between the 0037 and 1047 sets are 
flagged with ***. The differences between the 1047 and POSIX-BC sets 
are flagged with ###. All ord() numbers listed are decimal. If you 
would rather see this table listing octal values then run the table 
(that is, the pod version of this document since this recipe may not 
work with a pod2_other_format translation) through:

=over 4

=item recipe 0

=back

perl -ne 'if(/(.{43})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)/)' \
     -e '{printf("%s%-9.03o%-9.03o%-9.03o%.03o\n",$1,$2,$3,$4,$5)}' \
     perlebcdic.pod

If you want to retain the UTF-x code points then in script form you
might want to write:

=over 4

=item recipe 1

=back

open(FH,"<perlebcdic.pod") or die "Could not open perlebcdic.pod: $!";
 while (<FH>) {
 if (/(.{43})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\.?(\d*)\s+(\d+)\.?(\d*)/)
 {
 if ($7 ne '' && $9 ne '') {
 printf(
 "%s%-9.03o%-9.03o%-9.03o%-9.03o%-3o.%-5o%-3o.%.03o\n",
 $1,$2,$3,$4,$5,$6,$7,$8,$9);
 }
 elsif ($7 ne '') {
 printf("%s%-9.03o%-9.03o%-9.03o%-9.03o%-3o.%-5o%.03o\n",
 $1,$2,$3,$4,$5,$6,$7,$8);
 }
 else {
 printf("%s%-9.03o%-9.03o%-9.03o%-9.03o%-9.03o%.03o\n",
 $1,$2,$3,$4,$5,$6,$8);
 }
 }
 }

If you would rather see this table listing hexadecimal values then
run the table through:

=over 4

=item recipe 2

=back

perl -ne 'if(/(.{43})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)/)' \
     -e '{printf("%s%-9.02X%-9.02X%-9.02X%.02X\n",$1,$2,$3,$4,$5)}' \
     perlebcdic.pod

Or, in order to retain the UTF-x code points in hexadecimal:

=over 4

=item recipe 3

=back

open(FH,"<perlebcdic.pod") or die "Could not open perlebcdic.pod: $!";
 while (<FH>) {
 if (/(.{43})(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\.?(\d*)\s+(\d+)\.?(\d*)/)
 {
 if ($7 ne '' && $9 ne '') {
 printf(
 "%s%-9.02X%-9.02X%-9.02X%-9.02X%-2X.%-6.02X%02X.%02X\n",
 $1,$2,$3,$4,$5,$6,$7,$8,$9);
 }
 elsif ($7 ne '') {
 printf("%s%-9.02X%-9.02X%-9.02X%-9.02X%-2X.%-6.02X%02X\n",
 $1,$2,$3,$4,$5,$6,$7,$8);
 }
 else {
 printf("%s%-9.02X%-9.02X%-9.02X%-9.02X%-9.02X%02X\n",
 $1,$2,$3,$4,$5,$6,$8);
 }
 }
 }

ISO 8859-1 CCSID CCSID CCSID 1047
 chr CCSID 0819 0037 1047 POSIX-BC UTF-8 UTF-EBCDIC
 ----------------------------------------------------------------------------------------------
 <NULL> 0 0 0 0 0 0 
 <START OF HEADING> 1 1 1 1 1 1
 <START OF TEXT> 2 2 2 2 2 2
 <END OF TEXT> 3 3 3 3 3 3
 <END OF TRANSMISSION> 4 55 55 55 4 55 
 <ENQUIRY> 5 45 45 45 5 45 
 <ACKNOWLEDGE> 6 46 46 46 6 46 
 <BELL> 7 47 47 47 7 47 
 <BACKSPACE> 8 22 22 22 8 22 
 <HORIZONTAL TABULATION> 9 5 5 5 9 5 
 <LINE FEED> 10 37 21 21 10 21 ***
 <VERTICAL TABULATION> 11 11 11 11 11 11
 <FORM FEED> 12 12 12 12 12 12
 <CARRIAGE RETURN> 13 13 13 13 13 13
 <SHIFT OUT> 14 14 14 14 14 14
 <SHIFT IN> 15 15 15 15 15 15
 <DATA LINK ESCAPE> 16 16 16 16 16 16
 <DEVICE CONTROL ONE> 17 17 17 17 17 17
 <DEVICE CONTROL TWO> 18 18 18 18 18 18
 <DEVICE CONTROL THREE> 19 19 19 19 19 19
 <DEVICE CONTROL FOUR> 20 60 60 60 20 60
 <NEGATIVE ACKNOWLEDGE> 21 61 61 61 21 61
 <SYNCHRONOUS IDLE> 22 50 50 50 22 50
 <END OF TRANSMISSION BLOCK> 23 38 38 38 23 38
 <CANCEL> 24 24 24 24 24 24
 <END OF MEDIUM> 25 25 25 25 25 25
 <SUBSTITUTE> 26 63 63 63 26 63
 <ESCAPE> 27 39 39 39 27 39
 <FILE SEPARATOR> 28 28 28 28 28 28
 <GROUP SEPARATOR> 29 29 29 29 29 29
 <RECORD SEPARATOR> 30 30 30 30 30 30
 <UNIT SEPARATOR> 31 31 31 31 31 31
 <SPACE> 32 64 64 64 32 64
 ! 33 90 90 90 33 90
 " 34 127 127 127 34 127
 # 35 123 123 123 35 123
 $ 36 91 91 91 36 91
 % 37 108 108 108 37 108
 & 38 80 80 80 38 80
 ' 39 125 125 125 39 125
 ( 40 77 77 77 40 77
 ) 41 93 93 93 41 93
 * 42 92 92 92 42 92
 + 43 78 78 78 43 78
 , 44 107 107 107 44 107
 - 45 96 96 96 45 96
 . 46 75 75 75 46 75
 / 47 97 97 97 47 97
 0 48 240 240 240 48 240
 1 49 241 241 241 49 241
 2 50 242 242 242 50 242
 3 51 243 243 243 51 243
 4 52 244 244 244 52 244
 5 53 245 245 245 53 245
 6 54 246 246 246 54 246
 7 55 247 247 247 55 247
 8 56 248 248 248 56 248
 9 57 249 249 249 57 249
 : 58 122 122 122 58 122
 ; 59 94 94 94 59 94
 < 60 76 76 76 60 76
 = 61 126 126 126 61 126
 > 62 110 110 110 62 110
 ? 63 111 111 111 63 111
 @ 64 124 124 124 64 124
 A 65 193 193 193 65 193
 B 66 194 194 194 66 194
 C 67 195 195 195 67 195
 D 68 196 196 196 68 196
 E 69 197 197 197 69 197
 F 70 198 198 198 70 198
 G 71 199 199 199 71 199
 H 72 200 200 200 72 200
 I 73 201 201 201 73 201
 J 74 209 209 209 74 209
 K 75 210 210 210 75 210
 L 76 211 211 211 76 211
 M 77 212 212 212 77 212
 N 78 213 213 213 78 213
 O 79 214 214 214 79 214
 P 80 215 215 215 80 215
 Q 81 216 216 216 81 216
 R 82 217 217 217 82 217
 S 83 226 226 226 83 226
 T 84 227 227 227 84 227
 U 85 228 228 228 85 228
 V 86 229 229 229 86 229
 W 87 230 230 230 87 230
 X 88 231 231 231 88 231
 Y 89 232 232 232 89 232
 Z 90 233 233 233 90 233
 [ 91 186 173 187 91 173 *** ###
 \ 92 224 224 188 92 224 ### 
 ] 93 187 189 189 93 189 ***
 ^ 94 176 95 106 94 95 *** ###
 _ 95 109 109 109 95 109
 ` 96 121 121 74 96 121 ###
 a 97 129 129 129 97 129
 b 98 130 130 130 98 130
 c 99 131 131 131 99 131
 d 100 132 132 132 100 132
 e 101 133 133 133 101 133
 f 102 134 134 134 102 134
 g 103 135 135 135 103 135
 h 104 136 136 136 104 136
 i 105 137 137 137 105 137
 j 106 145 145 145 106 145
 k 107 146 146 146 107 146
 l 108 147 147 147 108 147
 m 109 148 148 148 109 148
 n 110 149 149 149 110 149
 o 111 150 150 150 111 150
 p 112 151 151 151 112 151
 q 113 152 152 152 113 152
 r 114 153 153 153 114 153
 s 115 162 162 162 115 162
 t 116 163 163 163 116 163
 u 117 164 164 164 117 164
 v 118 165 165 165 118 165
 w 119 166 166 166 119 166
 x 120 167 167 167 120 167
 y 121 168 168 168 121 168
 z 122 169 169 169 122 169
 { 123 192 192 251 123 192 ###
 | 124 79 79 79 124 79
 } 125 208 208 253 125 208 ###
 ~ 126 161 161 255 126 161 ###
 <DELETE> 127 7 7 7 127 7
 <PADDING CHARACTER> 128 32 32 32 194.128 32
 <HIGH OCTET PRESET> 129 33 33 33 194.129 33
 <BREAK PERMITTED HERE> 130 34 34 34 194.130 34
 <NO BREAK HERE> 131 35 35 35 194.131 35
 <INDEX> 132 36 36 36 194.132 36
 <NEXT LINE> 133 21 37 37 194.133 37 ***
 <START OF SELECTED AREA> 134 6 6 6 194.134 6
 <END OF SELECTED AREA> 135 23 23 23 194.135 23
 <CHARACTER TABULATION SET> 136 40 40 40 194.136 40
 <CHARACTER TABULATION WITH JUSTIFICATION> 137 41 41 41 194.137 41
 <LINE TABULATION SET> 138 42 42 42 194.138 42
 <PARTIAL LINE FORWARD> 139 43 43 43 194.139 43
 <PARTIAL LINE BACKWARD> 140 44 44 44 194.140 44
 <REVERSE LINE FEED> 141 9 9 9 194.141 9
 <SINGLE SHIFT TWO> 142 10 10 10 194.142 10
 <SINGLE SHIFT THREE> 143 27 27 27 194.143 27
 <DEVICE CONTROL STRING> 144 48 48 48 194.144 48
 <PRIVATE USE ONE> 145 49 49 49 194.145 49
 <PRIVATE USE TWO> 146 26 26 26 194.146 26
 <SET TRANSMIT STATE> 147 51 51 51 194.147 51
 <CANCEL CHARACTER> 148 52 52 52 194.148 52
 <MESSAGE WAITING> 149 53 53 53 194.149 53
 <START OF GUARDED AREA> 150 54 54 54 194.150 54
 <END OF GUARDED AREA> 151 8 8 8 194.151 8
 <START OF STRING> 152 56 56 56 194.152 56
 <SINGLE GRAPHIC CHARACTER INTRODUCER> 153 57 57 57 194.153 57
 <SINGLE CHARACTER INTRODUCER> 154 58 58 58 194.154 58
 <CONTROL SEQUENCE INTRODUCER> 155 59 59 59 194.155 59
 <STRING TERMINATOR> 156 4 4 4 194.156 4
 <OPERATING SYSTEM COMMAND> 157 20 20 20 194.157 20
 <PRIVACY MESSAGE> 158 62 62 62 194.158 62
 <APPLICATION PROGRAM COMMAND> 159 255 255 95 194.159 255 ###
 <NON-BREAKING SPACE> 160 65 65 65 194.160 128.65
 <INVERTED EXCLAMATION MARK> 161 170 170 170 194.161 128.66
 <CENT SIGN> 162 74 74 176 194.162 128.67 ###
 <POUND SIGN> 163 177 177 177 194.163 128.68
 <CURRENCY SIGN> 164 159 159 159 194.164 128.69
 <YEN SIGN> 165 178 178 178 194.165 128.70
 <BROKEN BAR> 166 106 106 208 194.166 128.71 ###
 <SECTION SIGN> 167 181 181 181 194.167 128.72
 <DIAERESIS> 168 189 187 121 194.168 128.73 *** ###
 <COPYRIGHT SIGN> 169 180 180 180 194.169 128.74
 <FEMININE ORDINAL INDICATOR> 170 154 154 154 194.170 128.81
 <LEFT POINTING GUILLEMET> 171 138 138 138 194.171 128.82
 <NOT SIGN> 172 95 176 186 194.172 128.83 *** ###
 <SOFT HYPHEN> 173 202 202 202 194.173 128.84
 <REGISTERED TRADE MARK SIGN> 174 175 175 175 194.174 128.85
 <MACRON> 175 188 188 161 194.175 128.86 ###
 <DEGREE SIGN> 176 144 144 144 194.176 128.87
 <PLUS-OR-MINUS SIGN> 177 143 143 143 194.177 128.88
 <SUPERSCRIPT TWO> 178 234 234 234 194.178 128.89
 <SUPERSCRIPT THREE> 179 250 250 250 194.179 128.98
 <ACUTE ACCENT> 180 190 190 190 194.180 128.99
 <MICRO SIGN> 181 160 160 160 194.181 128.100
 <PARAGRAPH SIGN> 182 182 182 182 194.182 128.101
 <MIDDLE DOT> 183 179 179 179 194.183 128.102
 <CEDILLA> 184 157 157 157 194.184 128.103
 <SUPERSCRIPT ONE> 185 218 218 218 194.185 128.104
 <MASC. ORDINAL INDICATOR> 186 155 155 155 194.186 128.105
 <RIGHT POINTING GUILLEMET> 187 139 139 139 194.187 128.106
 <FRACTION ONE QUARTER> 188 183 183 183 194.188 128.112
 <FRACTION ONE HALF> 189 184 184 184 194.189 128.113
 <FRACTION THREE QUARTERS> 190 185 185 185 194.190 128.114
 <INVERTED QUESTION MARK> 191 171 171 171 194.191 128.115
 <A WITH GRAVE> 192 100 100 100 195.128 138.65
 <A WITH ACUTE> 193 101 101 101 195.129 138.66
 <A WITH CIRCUMFLEX> 194 98 98 98 195.130 138.67
 <A WITH TILDE> 195 102 102 102 195.131 138.68
 <A WITH DIAERESIS> 196 99 99 99 195.132 138.69
 <A WITH RING ABOVE> 197 103 103 103 195.133 138.70
 <CAPITAL LIGATURE AE> 198 158 158 158 195.134 138.71
 <C WITH CEDILLA> 199 104 104 104 195.135 138.72
 <E WITH GRAVE> 200 116 116 116 195.136 138.73
 <E WITH ACUTE> 201 113 113 113 195.137 138.74
 <E WITH CIRCUMFLEX> 202 114 114 114 195.138 138.81
 <E WITH DIAERESIS> 203 115 115 115 195.139 138.82
 204 120 120 120 195.140 138.83
 205 117 117 117 195.141 138.84
 206 118 118 118 195.142 138.85
 207 119 119 119 195.143 138.86
 <CAPITAL LETTER ETH> 208 172 172 172 195.144 138.87
 <N WITH TILDE> 209 105 105 105 195.145 138.88
 <O WITH GRAVE> 210 237 237 237 195.146 138.89
 <O WITH ACUTE> 211 238 238 238 195.147 138.98
 <O WITH CIRCUMFLEX> 212 235 235 235 195.148 138.99
 <O WITH TILDE> 213 239 239 239 195.149 138.100
 <O WITH DIAERESIS> 214 236 236 236 195.150 138.101
 <MULTIPLICATION SIGN> 215 191 191 191 195.151 138.102
 <O WITH STROKE> 216 128 128 128 195.152 138.103
 217 253 253 224 195.153 138.104 ###
 218 254 254 254 195.154 138.105
 219 251 251 221 195.155 138.106 ###
 220 252 252 252 195.156 138.112
 <Y WITH ACUTE> 221 173 186 173 195.157 138.113 *** ###
 <CAPITAL LETTER THORN> 222 174 174 174 195.158 138.114
 223 89 89 89 195.159 138.115
 <a WITH GRAVE> 224 68 68 68 195.160 139.65
 <a WITH ACUTE> 225 69 69 69 195.161 139.66
 <a WITH CIRCUMFLEX> 226 66 66 66 195.162 139.67
 <a WITH TILDE> 227 70 70 70 195.163 139.68
 <a WITH DIAERESIS> 228 67 67 67 195.164 139.69
 <a WITH RING ABOVE> 229 71 71 71 195.165 139.70
 230 156 156 156 195.166 139.71
 <c WITH CEDILLA> 231 72 72 72 195.167 139.72
 <e WITH GRAVE> 232 84 84 84 195.168 139.73
 <e WITH ACUTE> 233 81 81 81 195.169 139.74
 <e WITH CIRCUMFLEX> 234 82 82 82 195.170 139.81
 <e WITH DIAERESIS> 235 83 83 83 195.171 139.82
 236 88 88 88 195.172 139.83
 237 85 85 85 195.173 139.84
 238 86 86 86 195.174 139.85
 239 87 87 87 195.175 139.86
 240 140 140 140 195.176 139.87
 <n WITH TILDE> 241 73 73 73 195.177 139.88
 <o WITH GRAVE> 242 205 205 205 195.178 139.89
 <o WITH ACUTE> 243 206 206 206 195.179 139.98
 <o WITH CIRCUMFLEX> 244 203 203 203 195.180 139.99
 <o WITH TILDE> 245 207 207 207 195.181 139.100
 <o WITH DIAERESIS> 246 204 204 204 195.182 139.101
 <DIVISION SIGN> 247 225 225 225 195.183 139.102
 <o WITH STROKE> 248 112 112 112 195.184 139.103
 249 221 221 192 195.185 139.104 ###
 250 222 222 222 195.186 139.105
 251 219 219 219 195.187 139.106
 252 220 220 220 195.188 139.112
 <y WITH ACUTE> 253 141 141 141 195.189 139.113
 254 142 142 142 195.190 139.114
 <y WITH DIAERESIS> 255 223 223 223 195.191 139.115

If you would rather see the above table in CCSID 0037 order rather than
ASCII + Latin-1 order then run the table through:

=over 4

=item recipe 4

=back

perl \
 -ne 'if(/.{43}\d{1,3}\s{6,8}\d{1,3}\s{6,8}\d{1,3}\s{6,8}\d{1,3}/)'\
 -e '{push(@l,$_)}' \
 -e 'END{print map{$_->[0]}' \
 -e ' sort{$a->[1] <=> $b->[1]}' \
 -e ' map{[$_,substr($_,52,3)]}@l;}' perlebcdic.pod

If you would rather see it in CCSID 1047 order then change the number
52 in the last line to 61, like this:

=over 4

=item recipe 5

=back

perl \
 -ne 'if(/.{43}\d{1,3}\s{6,8}\d{1,3}\s{6,8}\d{1,3}\s{6,8}\d{1,3}/)'\
 -e '{push(@l,$_)}' \
 -e 'END{print map{$_->[0]}' \
 -e ' sort{$a->[1] <=> $b->[1]}' \
 -e ' map{[$_,substr($_,61,3)]}@l;}' perlebcdic.pod

If you would rather see it in POSIX-BC order then change the number
61 in the last line to 70, like this:

=over 4

=item recipe 6

=back

=head1 IDENTIFYING CHARACTER CODE SETS

To determine the character set you are running under from perl one 
could use the return value of ord() or chr() to test one or more 
character values.  For example:

$is_ascii  = "A" eq chr(65);
    $is_ebcdic = "A" eq chr(193);

Also, "\t" is a C<HORIZONTAL TABULATION> character so that:

$is_ascii  = ord("\t") == 9;
    $is_ebcdic = ord("\t") == 5;

To distinguish EBCDIC code pages try looking at one or more of
the characters that differ between them.  For example:

$is_ebcdic_37   = "\n" eq chr(37);
    $is_ebcdic_1047 = "\n" eq chr(21);

Or better still choose a character that is uniquely encoded in any
of the code sets, e.g.:

$is_ascii           = ord('[') == 91;
    $is_ebcdic_37       = ord('[') == 186;
    $is_ebcdic_1047     = ord('[') == 173;
    $is_ebcdic_POSIX_BC = ord('[') == 187;

However, it would be unwise to write tests such as:

$is_ascii = "\r" ne chr(13);  #  WRONG
    $is_ascii = "\n" ne chr(10);  #  ILL ADVISED

Obviously the first of these will fail to distinguish most ASCII platforms
from either a CCSID 0037, a 1047, or a POSIX-BC EBCDIC platform since "\r" eq 
chr(13) under all of those coded character sets. But note too that 
because "\n" is chr(13) and "\r" is chr(10) on the Macintosh (which is an 
ASCII platform) the second C<$is_ascii> test will lead to trouble there.

To determine whether or not perl was built under an EBCDIC 
code page you can use the Config module like so:

use Config;
    $is_ebcdic = $Config{'ebcdic'} eq 'define';

=head1 CONVERSIONS

=head2 tr///

In order to convert a string of characters from one character set to 
another a simple list of numbers, such as in the right columns in the
above table, along with perl's tr/// operator is all that is needed.  
The data in the table are in ASCII/Latin1 order, hence the EBCDIC columns
provide easy-to-use ASCII/Latin1 to EBCDIC operations that are also easily 
reversed.

For example, to convert ASCII/Latin1 to code page 037 take the output of the
second numbers column from the output of recipe 2 (modified to add '\'
characters) and use it in tr/// like so:

$cp_037 = 
    '\x00\x01\x02\x03\x37\x2D\x2E\x2F\x16\x05\x25\x0B\x0C\x0D\x0E\x0F' .
    '\x10\x11\x12\x13\x3C\x3D\x32\x26\x18\x19\x3F\x27\x1C\x1D\x1E\x1F' .
    '\x40\x5A\x7F\x7B\x5B\x6C\x50\x7D\x4D\x5D\x5C\x4E\x6B\x60\x4B\x61' .
    '\xF0\xF1\xF2\xF3\xF4\xF5\xF6\xF7\xF8\xF9\x7A\x5E\x4C\x7E\x6E\x6F' .
    '\x7C\xC1\xC2\xC3\xC4\xC5\xC6\xC7\xC8\xC9\xD1\xD2\xD3\xD4\xD5\xD6' .
    '\xD7\xD8\xD9\xE2\xE3\xE4\xE5\xE6\xE7\xE8\xE9\xBA\xE0\xBB\xB0\x6D' .
    '\x79\x81\x82\x83\x84\x85\x86\x87\x88\x89\x91\x92\x93\x94\x95\x96' .
    '\x97\x98\x99\xA2\xA3\xA4\xA5\xA6\xA7\xA8\xA9\xC0\x4F\xD0\xA1\x07' .
    '\x20\x21\x22\x23\x24\x15\x06\x17\x28\x29\x2A\x2B\x2C\x09\x0A\x1B' .
    '\x30\x31\x1A\x33\x34\x35\x36\x08\x38\x39\x3A\x3B\x04\x14\x3E\xFF' .
    '\x41\xAA\x4A\xB1\x9F\xB2\x6A\xB5\xBD\xB4\x9A\x8A\x5F\xCA\xAF\xBC' .
    '\x90\x8F\xEA\xFA\xBE\xA0\xB6\xB3\x9D\xDA\x9B\x8B\xB7\xB8\xB9\xAB' .
    '\x64\x65\x62\x66\x63\x67\x9E\x68\x74\x71\x72\x73\x78\x75\x76\x77' .
    '\xAC\x69\xED\xEE\xEB\xEF\xEC\xBF\x80\xFD\xFE\xFB\xFC\xAD\xAE\x59' .
    '\x44\x45\x42\x46\x43\x47\x9C\x48\x54\x51\x52\x53\x58\x55\x56\x57' .
    '\x8C\x49\xCD\xCE\xCB\xCF\xCC\xE1\x70\xDD\xDE\xDB\xDC\x8D\x8E\xDF';

my $ebcdic_string = $ascii_string;
    eval '$ebcdic_string =~ tr/\000-\377/' . $cp_037 . '/';

To convert from EBCDIC 037 to ASCII just reverse the order of the tr///
arguments like so:

my $ascii_string = $ebcdic_string;
    eval '$ascii_string =~ tr/' . $cp_037 . '/\000-\377/';

Similarly one could take the output of the third numbers column from recipe 2
to obtain a C<$cp_1047> table. The fourth numbers column of the output from
recipe 2 could provide a C<$cp_posix_bc> table suitable for transcoding as
well.

If you wanted to see the inverse tables, you would first have to sort on the
desired numbers column as in recipes 4, 5 or 6, then take the output of the
first numbers column.

=head2 iconv

XPG operability often implies the presence of an I<iconv> utility
available from the shell or from the C library. Consult your system's
documentation for information on iconv.

On OS/390 or z/OS see the iconv(1) manpage.  One way to invoke the iconv 
shell utility from within perl would be to:

# OS/390 or z/OS example
    $ascii_data = `echo '$ebcdic_data'| iconv -f IBM-1047 -t ISO8859-1`

or the inverse map:

# OS/390 or z/OS example
    $ebcdic_data = `echo '$ascii_data'| iconv -f ISO8859-1 -t IBM-1047`

For other perl-based conversion options see the Convert::* modules on CPAN.

=head2 C RTL

The OS/390 and z/OS C run-time libraries provide _atoe() and _etoa() functions.

=head1 OPERATOR DIFFERENCES

The C<..> range operator treats certain character ranges with 
care on EBCDIC platforms. For example the following array
will have twenty six elements on either an EBCDIC platform
or an ASCII platform:

@alphabet = ('A'..'Z');   #  $#alphabet == 25

The bitwise operators such as & ^ | may return different results
when operating on string or character data in a perl program running 
on an EBCDIC platform than when run on an ASCII platform. Here is
an example adapted from the one in L<perlop>:

# EBCDIC-based examples
 print "j p \n" ^ " a h"; # prints "JAPH\n"
 print "JA" | " ph\n"; # prints "japh\n" 
 print "JAPH\nJunk" & "\277\277\277\277\277"; # prints "japh\n";
 print 'p N$' ^ " E<H\n"; # prints "Perl\n";

An interesting property of the 32 C0 control characters
in the ASCII table is that they can "literally" be constructed
as control characters in perl, e.g. C<(chr(0)> eq C<\c@>)>
C<(chr(1)> eq C<\cA>)>, and so on. Perl on EBCDIC platforms has been
ported to take C<\c@> to chr(0) and C<\cA> to chr(1), etc. as well, but the
thirty three characters that result depend on which code page you are
using. The table below uses the standard acronyms for the controls.
The POSIX-BC and 1047 sets are
identical throughout this range and differ from the 0037 set at only 
one spot (21 decimal). Note that the C<LINE FEED> character
may be generated by C<\cJ> on ASCII platforms but by C<\cU> on 1047 or POSIX-BC 
platforms and cannot be generated as a C<"\c.letter."> control character on 
0037 platforms. Note also that C<\c\> cannot be the final element in a string
or regex, as it will absorb the terminator. But C<\c\I<X>> is a C<FILE
SEPARATOR> concatenated with I<X> for all I<X>.

chr ord 8859-1 0037 1047 && POSIX-BC 
 -----------------------------------------------------------------------
 \c? 127 <DEL> " " 
 \c@ 0 <NUL> <NUL> <NUL>
 \cA 1 <SOH> <SOH> <SOH> 
 \cB 2 <STX> <STX> <STX>
 \cC 3 <ETX> <ETX> <ETX>
 \cD 4 <EOT> <ST> <ST> 
 \cE 5 <ENQ> <HT> <HT> 
 \cF 6 <ACK> <SSA> <SSA> 
 \cG 7 <BEL> <DEL> <DEL> 
 \cH 8 <BS> <EPA> <EPA> 
 \cI 9 <HT> <RI> <RI> 
 \cJ 10 <LF> <SS2> <SS2> 
 \cK 11 <VT> <VT> <VT>
 \cL 12 <FF> <FF> <FF> 
 \cM 13 <CR> <CR> <CR> 
 \cN 14 <SO> <SO> <SO>
 \cO 15 <SI> <SI> <SI>
 \cP 16 <DLE> <DLE> <DLE> 
 \cQ 17 <DC1> <DC1> <DC1>
 \cR 18 <DC2> <DC2> <DC2>
 \cS 19 <DC3> <DC3> <DC3> 
 \cT 20 <DC4> <OSC> <OSC> 
 \cU 21 <NAK> <NEL> <LF> ***
 \cV 22 <SYN> <BS> <BS>
 \cW 23 <ETB> <ESA> <ESA> 
 \cX 24 <CAN> <CAN> <CAN>
 \cY 25 <EOM> <EOM> <EOM>
 \cZ 26 <PU2> <PU2> 
 \c[ 27 <ESC> <SS3> <SS3> 
 \c\X 28 <FS>X <FS>X <FS>X
 \c] 29 <GS> <GS> <GS>
 \c^ 30 <RS> <RS> <RS>
 \c_ 31 <US> <US> <US>

=head1 FUNCTION DIFFERENCES

=over 8

=item chr()

chr() must be given an EBCDIC code number argument to yield a desired 
character return value on an EBCDIC platform.  For example:

$CAPITAL_LETTER_A = chr(193);

=item ord()

ord() will return EBCDIC code number values on an EBCDIC platform.
For example:

$the_number_193 = ord("A");

=item pack()

The c and C templates for pack() are dependent upon character set 
encoding.  Examples of usage on EBCDIC include:

$foo = pack("CCCC",193,194,195,196);
    # $foo eq "ABCD"
    $foo = pack("C4",193,194,195,196);
    # same thing

$foo = pack("ccxxcc",193,194,195,196);
    # $foo eq "AB\0\0CD"

=item print()

One must be careful with scalars and strings that are passed to
print that contain ASCII encodings.  One common place
for this to occur is in the output of the MIME type header for
CGI script writing.  For example, many perl programming guides 
recommend something similar to:

print "Content-type:\ttext/html\015\012\015\012"; 
    # this may be wrong on EBCDIC

Under the IBM OS/390 USS Web Server or WebSphere on z/OS for example 
you should instead write that as:

print "Content-type:\ttext/html\r\n\r\n"; # OK for DGW et al

That is because the translation from EBCDIC to ASCII is done
by the web server in this case (such code will not be appropriate for
the Macintosh however).  Consult your web server's documentation for 
further details.

=item printf()

The formats that can convert characters to numbers and vice versa
will be different from their ASCII counterparts when executed
on an EBCDIC platform.  Examples include:

printf("%c%c%c",193,194,195);  # prints ABC

=item sort()

EBCDIC sort results may differ from ASCII sort results especially for 
mixed case strings.  This is discussed in more detail below.

=item sprintf()

See the discussion of printf() above.  An example of the use
of sprintf would be:

$CAPITAL_LETTER_A = sprintf("%c",193);

=item unpack()

See the discussion of pack() above.

=back

=head1 REGULAR EXPRESSION DIFFERENCES

As of perl 5.005_03 the letter range regular expressions such as 
[A-Z] and [a-z] have been especially coded to not pick up gap 
characters. For example, characters such as E<ocirc> C<o WITH CIRCUMFLEX> 
that lie between I and J would not be matched by the 
regular expression range C</[H-K]/>. This works in
the other direction, too, if either of the range end points is
explicitly numeric: C<[\x89-\x91]> will match C<\x8e>, even
though C<\x89> is C and C<\x91 > is C<j>, and C<\x8e>
is a gap character from the alphabetic viewpoint.

If you do want to match the alphabet gap characters in a single octet 
regular expression try matching the hex or octal code such 
as C</\313/> on EBCDIC or C</\364/> on ASCII platforms to 
have your regular expression match C<o WITH CIRCUMFLEX>.

Another construct to be wary of is the inappropriate use of hex or
octal constants in regular expressions.  Consider the following
set of subs:

sub is_c0 {
        my $char = substr(shift,0,1);
        $char =~ /[\000-\037]/;
    }

sub is_print_ascii {
        my $char = substr(shift,0,1);
        $char =~ /[\040-\176]/;
    }

sub is_delete {
        my $char = substr(shift,0,1);
        $char eq "\177";
    }

sub is_c1 {
        my $char = substr(shift,0,1);
        $char =~ /[\200-\237]/;
    }

sub is_latin_1 {
        my $char = substr(shift,0,1);
        $char =~ /[\240-\377]/;
    }

The above would be adequate if the concern was only with numeric code points.
However, the concern may be with characters rather than code points 
and on an EBCDIC platform it may be desirable for constructs such as 
C<if (is_print_ascii("A")) {print "A is a printable character\n";}> to print
out the expected message. One way to represent the above collection
of character classification subs that is capable of working across the
four coded character sets discussed in this document is as follows:

sub Is_c0 {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char =~ /[\000-\037]/;
        } 
        if (ord('^')==176) { # 0037
            return $char =~ /[\000-\003\067\055-\057\026\005\045\013-\023\074\075\062\046\030\031\077\047\034-\037]/;
        }
        if (ord('^')==95 || ord('^')==106) { # 1047 || posix-bc
            return $char =~ /[\000-\003\067\055-\057\026\005\025\013-\023\074\075\062\046\030\031\077\047\034-\037]/;
        }
    }

sub Is_print_ascii {
 my $char = substr(shift,0,1);
 $char =~ /[ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/;
 }

sub Is_delete {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char eq "\177";
        }
        else  {              # ebcdic
            return $char eq "\007";
        }
    }

sub Is_c1 {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char =~ /[\200-\237]/;
        }
        if (ord('^')==176) { # 0037
            return $char =~ /[\040-\044\025\006\027\050-\054\011\012\033\060\061\032\063-\066\010\070-\073\040\024\076\377]/;
        }
        if (ord('^')==95)  { # 1047
            return $char =~ /[\040-\045\006\027\050-\054\011\012\033\060\061\032\063-\066\010\070-\073\040\024\076\377]/;
        }
        if (ord('^')==106) { # posix-bc
            return $char =~ 
              /[\040-\045\006\027\050-\054\011\012\033\060\061\032\063-\066\010\070-\073\040\024\076\137]/;
        }
    }

sub Is_latin_1 {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char =~ /[\240-\377]/;
        }
        if (ord('^')==176) { # 0037
            return $char =~ 
              /[\101\252\112\261\237\262\152\265\275\264\232\212\137\312\257\274\220\217\352\372\276\240\266\263\235\332\233\213\267\270\271\253\144\145\142\146\143\147\236\150\164\161-\163\170\165-\167\254\151\355\356\353\357\354\277\200\375\376\373\374\255\256\131\104\105\102\106\103\107\234\110\124\121-\123\130\125-\127\214\111\315\316\313\317\314\341\160\335\336\333\334\215\216\337]/;
        }
        if (ord('^')==95)  { # 1047
            return $char =~
              /[\101\252\112\261\237\262\152\265\273\264\232\212\260\312\257\274\220\217\352\372\276\240\266\263\235\332\233\213\267\270\271\253\144\145\142\146\143\147\236\150\164\161-\163\170\165-\167\254\151\355\356\353\357\354\277\200\375\376\373\374\272\256\131\104\105\102\106\103\107\234\110\124\121-\123\130\125-\127\214\111\315\316\313\317\314\341\160\335\336\333\334\215\216\337]/; 
        }
        if (ord('^')==106) { # posix-bc
            return $char =~ 
              /[\101\252\260\261\237\262\320\265\171\264\232\212\272\312\257\241\220\217\352\372\276\240\266\263\235\332\233\213\267\270\271\253\144\145\142\146\143\147\236\150\164\161-\163\170\165-\167\254\151\355\356\353\357\354\277\200\340\376\335\374\255\256\131\104\105\102\106\103\107\234\110\124\121-\123\130\125-\127\214\111\315\316\313\317\314\341\160\300\336\333\334\215\216\337]/;
        }
    }

Note however that only the C<Is_ascii_print()> sub is really independent 
of coded character set. Another way to write C<Is_latin_1()> would be 
to use the characters in the range explicitly:

Although that form may run into trouble in network transit (due to the 
presence of 8 bit characters) or on non ISO-Latin character sets.

=head1 SOCKETS

Most socket programming assumes ASCII character encodings in network
byte order.  Exceptions can include CGI script writing under a
host web server where the server may take care of translation for you.
Most host web servers convert EBCDIC data to ISO-8859-1 or Unicode on
output.

=head1 SORTING

One big difference between ASCII-based character sets and EBCDIC ones
are the relative positions of upper and lower case letters and the
letters compared to the digits.  If sorted on an ASCII-based platform the
two-letter abbreviation for a physician comes before the two letter
abbreviation for drive; that is:

@sorted = sort(qw(Dr. dr.));  # @sorted holds ('Dr.','dr.') on ASCII,
                                  # but ('dr.','Dr.') on EBCDIC

The property of lowercase before uppercase letters in EBCDIC is
even carried to the Latin 1 EBCDIC pages such as 0037 and 1047.
An example would be that E<Euml> C<E WITH DIAERESIS> (203) comes 
before E<euml> C<e WITH DIAERESIS> (235) on an ASCII platform, but 
the latter (83) comes before the former (115) on an EBCDIC platform. 
(Astute readers will note that the uppercase version of E<szlig> 
C is simply "SS" and that the upper case version of 
E<yuml> C<y WITH DIAERESIS> is not in the 0..255 range but it is 
at U+x0178 in Unicode, or C<"\x{178}"> in a Unicode enabled Perl).

The sort order will cause differences between results obtained on
ASCII platforms versus EBCDIC platforms.  What follows are some suggestions
on how to deal with these differences.

=head2 Ignore ASCII vs. EBCDIC sort differences.

This is the least computationally expensive strategy.  It may require
some user education.

=head2 MONO CASE then sort data.

In order to minimize the expense of mono casing mixed-case text, try to
C<tr///> towards the character set case most employed within the data.
If the data are primarily UPPERCASE non Latin 1 then apply tr/[a-z]/[A-Z]/
then sort(). If the data are primarily lowercase non Latin 1 then
apply tr/[A-Z]/[a-z]/ before sorting. If the data are primarily UPPERCASE
and include Latin-1 characters then apply:

tr/[a-z]/[A-Z]/;
    tr/[Ã Ã¡Ã¢Ã£Ã¤Ã¥Ã¦Ã§Ã¨Ã©ÃªÃ«Ã¬ÃÃ®Ã¯Ã°Ã±Ã²Ã³Ã´ÃµÃ¶Ã¸Ã¹ÃºÃ»Ã¼Ã½Ã¾]/[ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃ/;
    s/Ã/SS/g;

then sort(). Do note however that such Latin-1 manipulation does not 
address the E<yuml> C<y WITH DIAERESIS> character that will remain at 
code point 255 on ASCII platforms, but 223 on most EBCDIC platforms 
where it will sort to a place less than the EBCDIC numerals. With a 
Unicode-enabled Perl you might try:

tr/^?/\x{178}/;

The strategy of mono casing data before sorting does not preserve the case 
of the data and may not be acceptable for that reason.

=head2 Convert, sort data, then re convert.

This is the most expensive proposition that does not employ a network
connection.

=head2 Perform sorting on one type of platform only.

This strategy can employ a network connection.  As such
it would be computationally expensive.

=head1 TRANSFORMATION FORMATS

There are a variety of ways of transforming data with an intra character set 
mapping that serve a variety of purposes.  Sorting was discussed in the 
previous section and a few of the other more popular mapping techniques are 
discussed next.

=head2 URL decoding and encoding

Note that some URLs have hexadecimal ASCII code points in them in an
attempt to overcome character or protocol limitation issues.  For example 
the tilde character is not on every keyboard hence a URL of the form:

http://www.pvhp.com/~pvhp/

may also be expressed as either of:

http://www.pvhp.com/%7Epvhp/

http://www.pvhp.com/%7epvhp/

where 7E is the hexadecimal ASCII code point for '~'.  Here is an example
of decoding such a URL under CCSID 1047:

$url = 'http://www.pvhp.com/%7Epvhp/';
    # this array assumes code page 1047
    my @a2e_1047 = (
          0,  1,  2,  3, 55, 45, 46, 47, 22,  5, 21, 11, 12, 13, 14, 15,
         16, 17, 18, 19, 60, 61, 50, 38, 24, 25, 63, 39, 28, 29, 30, 31,
         64, 90,127,123, 91,108, 80,125, 77, 93, 92, 78,107, 96, 75, 97,
        240,241,242,243,244,245,246,247,248,249,122, 94, 76,126,110,111,
        124,193,194,195,196,197,198,199,200,201,209,210,211,212,213,214,
        215,216,217,226,227,228,229,230,231,232,233,173,224,189, 95,109,
        121,129,130,131,132,133,134,135,136,137,145,146,147,148,149,150,
        151,152,153,162,163,164,165,166,167,168,169,192, 79,208,161,  7,
         32, 33, 34, 35, 36, 37,  6, 23, 40, 41, 42, 43, 44,  9, 10, 27,
         48, 49, 26, 51, 52, 53, 54,  8, 56, 57, 58, 59,  4, 20, 62,255,
         65,170, 74,177,159,178,106,181,187,180,154,138,176,202,175,188,
        144,143,234,250,190,160,182,179,157,218,155,139,183,184,185,171,
        100,101, 98,102, 99,103,158,104,116,113,114,115,120,117,118,119,
        172,105,237,238,235,239,236,191,128,253,254,251,252,186,174, 89,
         68, 69, 66, 70, 67, 71,156, 72, 84, 81, 82, 83, 88, 85, 86, 87,
        140, 73,205,206,203,207,204,225,112,221,222,219,220,141,142,223
    );
    $url =~ s/%([0-9a-fA-F]{2})/pack("c",$a2e_1047[hex($1)])/ge;

Conversely, here is a partial solution for the task of encoding such 
a URL under the 1047 code page:

$url = 'http://www.pvhp.com/~pvhp/';
 # this array assumes code page 1047
 my @e2a_1047 = (
 0, 1, 2, 3,156, 9,134,127,151,141,142, 11, 12, 13, 14, 15,
 16, 17, 18, 19,157, 10, 8,135, 24, 25,146,143, 28, 29, 30, 31,
 128,129,130,131,132,133, 23, 27,136,137,138,139,140, 5, 6, 7,
 144,145, 22,147,148,149,150, 4,152,153,154,155, 20, 21,158, 26,
 32,160,226,228,224,225,227,229,231,241,162, 46, 60, 40, 43,124,
 38,233,234,235,232,237,238,239,236,223, 33, 36, 42, 41, 59, 94,
 45, 47,194,196,192,193,195,197,199,209,166, 44, 37, 95, 62, 63,
 248,201,202,203,200,205,206,207,204, 96, 58, 35, 64, 39, 61, 34,
 216, 97, 98, 99,100,101,102,103,104,105,171,187,240,253,254,177,
 176,106,107,108,109,110,111,112,113,114,170,186,230,184,198,164,
 181,126,115,116,117,118,119,120,121,122,161,191,208, 91,222,174,
 172,163,165,183,169,167,182,188,189,190,221,168,175, 93,180,215,
 123, 65, 66, 67, 68, 69, 70, 71, 72, 73,173,244,246,242,243,245,
 125, 74, 75, 76, 77, 78, 79, 80, 81, 82,185,251,252,249,250,255,
 92,247, 83, 84, 85, 86, 87, 88, 89, 90,178,212,214,210,211,213,
 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,179,219,220,217,218,159
 );
 # The following regular expression does not address the 
 # mappings for: ('.' => '%2E', '/' => '%2F', ':' => '%3A') 
 $url =~ s/([\t "#%&,;<=>\?\@\[\\\]^`{|}~])/sprintf("%%%02X",$e2a_1047[ord($1)])/ge;

where a more complete solution would split the URL into components 
and apply a full s/// substitution only to the appropriate parts.

In the remaining examples a @e2a or @a2e array may be employed
but the assignment will not be shown explicitly.  For code page 1047
you could use the @a2e_1047 or @e2a_1047 arrays just shown.

=head2 uu encoding and decoding

The C template to pack() or unpack() will render EBCDIC data in EBCDIC 
characters equivalent to their ASCII counterparts. For example, the 
following will print "Yes indeed\n" on either an ASCII or EBCDIC computer:

$all_byte_chrs = '';
 for (0..255) { $all_byte_chrs .= chr($_); }
 $uuencode_byte_chrs = pack('u', $all_byte_chrs);
 ($uu = <<'ENDOFHEREDOC') =~ s/^\s*//gm;
 M``$"`P0%!@<("0H+#`T.#Q`1$A,4%187&!D:&QP='A\@(2(C)"4F)R@I*BLL
 M+2XO,#$R,S0U-C<X.3H[/#T^/T!!0D-$149'2$E*2TQ-3D]045)35%565UA9
 M6EM<75Y?8&%B8V1E9F=H:6IK;&UN;W!Q<G-T=79W>'EZ>WQ]?G^`@8*#A(6&
 MAXB)BHN,C8Z/D)&2DY25EI>8F9J;G)V>GZ"AHJ.DI::GJ*FJJZRMKJ^PL;*S
 MM+6VM[BYNKN\O;Z_P,'"P\3%QL?(R<K+S,W.S]#1TM/4U=;7V-G:V]S=WM_@
 ?X>+CY.7FY^CIZNOL[>[O\/'R\_3U]O?X^?K[_/W^_P``
 ENDOFHEREDOC
 if ($uuencode_byte_chrs eq $uu) {
 print "Yes ";
 }
 $uudecode_byte_chrs = unpack('u', $uuencode_byte_chrs);
 if ($uudecode_byte_chrs eq $all_byte_chrs) {
 print "indeed\n";
 }

Here is a very spartan uudecoder that will work on EBCDIC provided
that the @e2a array is filled in appropriately:

#!/usr/local/bin/perl
 @e2a = ( # this must be filled in
 );
 $_ = <> until ($mode,$file) = /^begin\s*(\d*)\s*(\S*)/;
 open(OUT, "> $file") if $file ne "";
 while(<>) {
 last if /^end/;
 next if /[a-z]/;
 next unless int(((($e2a[ord()] - 32 ) & 077) + 2) / 3) ==
 int(length() / 4);
 print OUT unpack("u", $_);
 }
 close(OUT);
 chmod oct($mode), $file;

=head2 Quoted-Printable encoding and decoding

On ASCII-encoded platforms it is possible to strip characters outside of
the printable set using:

# This QP encoder works on ASCII only
    $qp_string =~ s/([=\x00-\x1F\x80-\xFF])/sprintf("=%02X",ord($1))/ge;

Whereas a QP encoder that works on both ASCII and EBCDIC platforms 
would look somewhat like the following (where the EBCDIC branch @e2a 
array is omitted for brevity):

if (ord('A') == 65) { # ASCII
 $delete = "\x7F"; # ASCII
 @e2a = (0 .. 255) # ASCII to ASCII identity map
 }
 else { # EBCDIC
 $delete = "\x07"; # EBCDIC
 @e2a = # EBCDIC to ASCII map (as shown above)
 }
 $qp_string =~
 s/([^ !"\#\$%&'()*+,\-.\/0-9:;<>?\@A-Z[\\\]^_`a-z{|}~$delete])/sprintf("=%02X",$e2a[ord($1)])/ge;

(although in production code the substitutions might be done
in the EBCDIC branch with the @e2a array and separately in the 
ASCII branch without the expense of the identity map).

Such QP strings can be decoded with:

# This QP decoder is limited to ASCII only
    $string =~ s/=([0-9A-Fa-f][0-9A-Fa-f])/chr hex $1/ge;
    $string =~ s/=[\n\r]+$//;

Whereas a QP decoder that works on both ASCII and EBCDIC platforms 
would look somewhat like the following (where the @a2e array is
omitted for brevity):

$string =~ s/=([0-9A-Fa-f][0-9A-Fa-f])/chr $a2e[hex $1]/ge;
    $string =~ s/=[\n\r]+$//;

=head2 Caesarean ciphers

The practice of shifting an alphabet one or more characters for encipherment
dates back thousands of years and was explicitly detailed by Gaius Julius
Caesar in his B<Gallic Wars> text. A single alphabet shift is sometimes 
referred to as a rotation and the shift amount is given as a number $n after
the string 'rot' or "rot$n". Rot0 and rot26 would designate identity maps 
on the 26-letter English version of the Latin alphabet. Rot13 has the 
interesting property that alternate subsequent invocations are identity maps 
(thus rot13 is its own non-trivial inverse in the group of 26 alphabet 
rotations). Hence the following is a rot13 encoder and decoder that will 
work on ASCII and EBCDIC platforms:

#!/usr/local/bin/perl

while(<>){
 tr/n-za-mN-ZA-M/a-zA-Z/;
 print;
 }

In one-liner form:

perl -ne 'tr/n-za-mN-ZA-M/a-zA-Z/;print'

=head1 Hashing order and checksums

To the extent that it is possible to write code that depends on 
hashing order there may be differences between hashes as stored
on an ASCII-based platform and hashes stored on an EBCDIC-based platform.
XXX

=head1 I18N AND L10N

Internationalization (I18N) and localization (L10N) are supported at least 
in principle even on EBCDIC platforms. The details are system-dependent 
and discussed under the L<perlebcdic/OS ISSUES> section below.

=head1 MULTI-OCTET CHARACTER SETS

Perl may work with an internal UTF-EBCDIC encoding form for wide characters 
on EBCDIC platforms in a manner analogous to the way that it works with 
the UTF-8 internal encoding form on ASCII based platforms.

Legacy multi byte EBCDIC code pages XXX.

=head1 OS ISSUES

There may be a few system-dependent issues 
of concern to EBCDIC Perl programmers.

=head2 OS/400

=over 8

=item PASE

The PASE environment is a runtime environment for OS/400 that can run
executables built for PowerPC AIX in OS/400; see L<perlos400>. PASE
is ASCII-based, not EBCDIC-based as the ILE.

=item IFS access

XXX.

=back

=head2 OS/390, z/OS

Perl runs under Unix Systems Services or USS.

=over 8

=item chcp

B<chcp> is supported as a shell utility for displaying and changing 
one's code page. See also L<chcp(1)>.

=item dataset access

For sequential data set access try:

my @ds_records = `cat //DSNAME`;

or:

my @ds_records = `cat //'HLQ.DSNAME'`;

See also the OS390::Stdio module on CPAN.

=item OS/390, z/OS iconv

B<iconv> is supported as both a shell utility and a C RTL routine.
See also the iconv(1) and iconv(3) manual pages.

=item locales

On OS/390 or z/OS see L<locale> for information on locales. The L10N files
are in F</usr/nls/locale>. $Config{d_setlocale} is 'define' on OS/390
or z/OS.

=back

=head2 VM/ESA?

XXX.

=head2 POSIX-BC?

XXX.

=head1 BUGS

This pod document contains literal Latin 1 characters and may encounter 
translation difficulties. In particular one popular nroff implementation 
was known to strip accented characters to their unaccented counterparts 
while attempting to view this document through the B<pod2man> program 
(for example, you may see a plain C<y> rather than one with a diaeresis 
as in E<yuml>). Another nroff truncated the resultant manpage at
the first occurrence of 8 bit characters.

Not all shells will allow multiple C<-e> string arguments to perl to
be concatenated together properly as recipes 0, 2, 4, 5, and 6 might 
seem to imply.

=head1 SEE ALSO

L<perllocale>, L<perlfunc>, L<perlunicode>, L<utf8>.

=head1 REFERENCES

L<http://anubis.dkuug.dk/i18n/charmaps>

L<http://www.unicode.org/>

L<http://www.unicode.org/unicode/reports/tr16/>

L<http://www.wps.com/projects/codes/>
B<ASCII: American Standard Code for Information Infiltration> Tom Jennings,
September 1999.

B<The Unicode Standard, Version 3.0> The Unicode Consortium, Lisa Moore ed., 
ISBN 0-201-61633-5, Addison Wesley Developers Press, February 2000.

B<CDRA: IBM - Character Data Representation Architecture - 
Reference and Registry>, IBM SC09-2190-00, December 1996.

"Demystifying Character Sets", Andrea Vine, Multilingual Computing 
& Technology, B<#26 Vol. 10 Issue 4>, August/September 1999;
ISSN 1523-0309; Multilingual Computing Inc. Sandpoint ID, USA.

B<Codes, Ciphers, and Other Cryptic and Clandestine Communication>
Fred B. Wrixon, ISBN 1-57912-040-7, Black Dog & Leventhal Publishers,
1998.

L<http://www.bobbemer.com/P-BIT.HTM>
B<IBM - EBCDIC and the P-bit; The biggest Computer Goof Ever> Robert Bemer.

=head1 HISTORY

15 April 2001: added UTF-8 and UTF-EBCDIC to main table, pvhp.

=head1 AUTHOR

Peter Prymmer pvhp@best.com wrote this in 1999 and 2000 
with CCSID 0819 and 0037 help from Chris Leach and 
AndrE<eacute> Pirard A.Pirard@ulg.ac.be as well as POSIX-BC 
help from Thomas Dorner Thomas.Dorner@start.de.
Thanks also to Vickie Cooper, Philip Newton, William Raffloer, and 
Joe Smith. Trademarks, registered trademarks, service marks and 
registered service marks used in this document are the property of 
their respective owners.

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