UTF-EBCDIC

UTF-EBCDIC is a <a href="/facts/Character_encoding/ShJHIMoA">character encoding</a> capable of encoding all 1,112,064 valid character <a href="/facts/Code_point/R184ugJX">code points</a> in <a href="/facts/Unicode/DDu3MfPV">Unicode</a> using 1 to 5 <a href="/facts/Byte/BNHUp9Qq">bytes</a> (in contrast to a maximum of 4 for <a href="/facts/UTF-8/xlaVHSyf">UTF-8</a>). It is meant to be <a href="/facts/EBCDIC/qAhmvgj0">EBCDIC</a>-friendly, so that legacy EBCDIC applications on <a href="/facts/Mainframe_computer/nrBR6rWa">mainframes</a> may process the characters without much difficulty. Its advantages for existing EBCDIC-based systems are similar to <a href="/facts/UTF-8/xlaVHSyf">UTF-8</a>'s advantages for existing <a href="/facts/ASCII/vGUI33Qu">ASCII</a>-based systems. Details on UTF-EBCDIC are defined in Unicode Technical Report #16.
To produce the UTF-EBCDIC encoded version of a series of Unicode code points, an encoding based on UTF-8 (known in the specification as UTF-8-Mod) is applied first (creating what the specification calls an I8 sequence). The main difference between this encoding and UTF-8 is that it allows Unicode code points U+0080 through U+009F (the <a href="/facts/C1_control_code/bBp1dGVl">C1 control codes</a>) to be represented as a single byte and therefore later mapped to corresponding EBCDIC control codes. In order to achieve this, UTF-8-Mod uses 101xxxxx instead of 10xxxxxx as the format for trailing bytes in a multi-byte sequence. As this can only hold 5 bits rather than 6, the UTF-8-Mod encoding of codepoints above U+03FF are larger than the UTF-8 encoding.
The UTF-8-Mod transformation leaves the data in an ASCII-based format (for example, U+0041 "A" is still encoded as 0x41), so each byte is fed through a reversible (one-to-one) lookup table to produce the final UTF-EBCDIC encoding. For example, 0x41 in this table maps to 0xC1; thus the UTF-EBCDIC encoding of U+0041 (Unicode's "A") is 0xC1 (EBCDIC's "A").
UTF-EBCDIC is rarely used, even on the EBCDIC-based mainframes for which it was designed. <a href="/facts/IBM/QszA7nwd">IBM</a> EBCDIC-based mainframe operating systems, such as <a href="/facts/Z/OS/amLCAlgV">z/OS</a>, usually use <a href="/facts/UTF-16/ofSmbCem">UTF-16</a> for complete Unicode support. For example, <a href="/facts/IBM_Db2/2cYITuuY">IBM Db2</a>, <a href="/facts/COBOL/wVnhqs0k">COBOL</a>, <a href="/facts/PL/I/469mVYgd">PL/I</a>, <a href="/facts/Java_(programming_language)/9ScgFyAL">Java</a> and the <a href="/facts/IBM/QszA7nwd">IBM</a> <a href="/facts/XML/clNgUfWk">XML</a> toolkit support UTF-16 on IBM mainframes.

UTF-EBCDIC open-in-new

UTF-EBCDIC