On 6 April 2011, Jonathan Rochkind wrote:
> I think we computer programmers are really better-served by reserving the
> notion of "validity" for things specified by formal specifications -- as we
> normally do, talking about any other data format. And the only formal
> specifications I can find for Marc21 say that leader bytes 20-23 should be
> 4500. (Not true of Marc in general just Marc21).
"Validity" does mean something definite ... but Postel's Law is a good
guideline, especially with the swamp of bad MARC, old MARC, alternate
MARC, that's out there. Valid MARC is valid MARC, but if---for the sake
of file and its magic---we can identify technically invalid but still
usable MARC, that's good.
William Denton, Toronto : miskatonic.org www.frbr.org openfrbr.org