[Info-vax] Character sets

[Stephen Hoffman]

On 2022-09-02 18:15:42 +0000, Simon Clubley said:

> Any many Linux programmers would even know that such a thing 
> (predecessors to ISO 8859, and other character sets) exists, let alone 
> have any need to use it ?

I'm not aware of how widespread app usage of national character sets 
might be on OpenVMS, but DEC MCS / ISO Latin 1 and ODS-5 usage is 
arguably still "bleeding edge" on OpenVMS, and app and OpenVMS adoption 
of UTF-8 encoding is, well, negligible.

Migrating apps away from IBM EBCDIC, UNIVAC FIELDATA, DEC RADIX 50, or 
whatever encoding is entirely up to app developers and maintainers. =

OpenVMS has RADIX 50 tucked away in a few very dusty corners too, 
albeit still somewhat user-visible. But I digress.

Getting existing apps with older encodings migrated to current 
encodings including to UTF-8 is also largely left to app developers.

Or is entirely left to, in the case of OpenVMS, as OpenVMS has not 
adopted and has not integrated Unicode nor UTF-8 into the platform and 
its run-time libraries. Nor are any VSI plans to upgrade DCL to support 
UTF-8 at all likely to arise.

Little (nothing?) past the ODS-5 UTF-8 filename work exists with 
OpenVMS, and—as with most of the retrofit-compatible-hackery—that's 
less than easy for apps to use. You'll probably be using or porting 
recent versions of ICU, libunistring, or ilk, and the OpenVMS 32- and 
64-bit string descriptors are unfortunately also less than useful here 
around language and encoding. (This is where the object abstraction 
shines, too. It's what descriptors and itemlists evolved into, on other 
platforms.)

Pedant notes: yes, I do know about wchar_t and friends in C and C++, 
which is... a mess, and is also ill-suited for UTF-8.  Probably better 
to use char16_t and char32_t, if you do need fixed-width wide character 
storage. Here also intentionally excluding Java from this discussion, 
because, well, Java, and a central tenet of Java being efforts to 
isolate and exclude the platform from most app-related considerations.

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