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The American Standard Code for Information Interchange is a set of integers running from 0
to 127 (decimal) that imply character interpretation by the display and other system(s) 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 a "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.
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.
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).
The Extended Binary Coded Decimal Interchange Code refers to a large collection of slightly
different single and multi byte coded character sets that are different from ASCII or ISO
8859-1 and 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. Leading zero digits in CCSID numbers within this document are
insignificant. E.g. CCSID 0037 may be referred to as 37 in places.
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:
\ [ ] { } ^ ~ ! # | $ @ `
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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 37 differs from ISO 8859-1 in 237
places, in other words they agree on only 19 code point values.
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.
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.
In Unicode terminology a 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
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will hold. (If Unicode code points were applied consistently over all the possible code
points, pack("U",ord("A")) would in EBCDIC equal A with acute or
chr(101), and unpack("U", "A") would equal 65, or non-breaking space,
not 193, or ord "A".)
- Many of the remaining seem to be related to case-insensitive matching: for example,
/[\x{131}]/
(LATIN SMALL LETTER DOTLESS I) does not match "I" case-insensitively, as it
should under Unicode. (The match succeeds in ASCII-derived platforms.)
- The extensions Unicode::Collate and Unicode::Normalized are not supported under EBCDIC,
likewise for the encoding pragma.
UTF is a Unicode Transformation Format. UTF-8 is a Unicode conforming representation of the
Unicode standard that looks very much like ASCII. UTF-EBCDIC is an attempt to represent
Unicode characters in an EBCDIC transparent manner.
Starting from Perl 5.8 you can use the standard new module Encode to translate from EBCDIC
to Latin-1 code points
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
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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
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For doing I/O it is suggested that you use the autotranslating features of PerlIO, see perluniintro.
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