[Info-vax] VMS version numbers, was: Re: DCL enhancements

[Stephen Hoffman]

On 2021-01-27 18:33:53 +0000, Simon Clubley said:

> I wonder how much effort would be involved in adding support to VMS to 
> automatically shuffle down the existing file versions when something 
> tries to create a new version after ;32767 is reached on a file ?

It'll break (some) stuff, as ;32767 has long been used to disable 
file-creation activity in various contexts.

This deliberate ;32767 usage might be considered undocumented behavior, 
but new version creation stopping at ;32767 is documented.

Hyrum's: "With a sufficient number of users of an API, it does not 
matter what you promise in the contract: all observable behaviors of 
your system will be depended on by somebody."

Timing holes and all, the two-RENAME sequence commonly used for packing 
file versions has been in the FAQ for most of twenty years, if not 
longer.

http://www.hoffmanlabs.org/vmsfaq/vmsfaq_011.html#mgmtversions

File versions make for a rotten means of reverting, but versions and 
(more frequent) backups are what OpenVMS offers for reverting / undo 
support.


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