Code Page 21027 "Extended/Ext Alpha Lowercase"

I was playing with code pages and ran into an interesting case:  Code Page 21027 - Ext Alpha Lowercase. 

This code page has some interesting behavior.  It looks like a Japaneses EBCDIC code page, however its kind of "missing" mappings for some characters, like 8, 9, =, H, I, Q, R, Y, Z, Halfwidth Katakana Ku, and Halfwidth Katakana Nu.  If you try to convert these characters from Unicode to 21027 and back, you end up with other code points.  For example the Unicode character "8" (U+0038) changes to U+f8f8 when its round tripped in this code page.

If anyone has is using this code page or knows what its used for I'd be interested in hearing about it 🙂

In .Net v2.0 we've removed support for this code page, although it was available in v1.0 and v1.1 and continues to be available natively in Windows XP and Server 2003.

Comments (3)
  1. Late last month, I suggested that you probably don’t want to use Microsoft’s code page 20269 and then…

  2. Random832 says:

    Other than the missing characters, it looks like IBM Code Page 1027. This appears to be part of an MBCS scheme called CCSID 939.

    1. Random832, Yippy, almost 11 years later I get a plausible answer! 🙂 The naming (21027 vs 1027) would seem to hint at that as well. If so, 21027 is clearly incomplete. Nobody’s complained about it being missing from .Net, so I guess there’s that.

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