On Apr 3, 2008, at 10:31, Schuh, Richard wrote:
And a physical record, otherwise known as a block is the type of
record
to which I was referring. The count field, the C of CKD, that has
zeros
for both the key and the data lengths is what signals an empty block,
er, physical record.
I would be very surprised if CMS ever wrote such a record in either
file
system. That would destroy the formatting of the remainder of the
track
because Write CKD is a formatting write.
Exactly. In the Bad Old Days, I was able to make a single byte zap
to the CMS nucleus (my virtual machine only; CC mask in a BC) and
write zero-length records to RECFM=V MDFS files. I could read them
successfully with an assembler program. However many utilities
program checked on such files (BCTR; EX; MVC?) I still see no
valid rationale for imposing such a constraint on programmers;
it greatly limits portability of programs.
-- gil
