On Sat, 11 Nov 2023 08:59:07 -0500, David S. wrote:
>    ...
. Sequential processing
>*must* begin at specified starting point and there can be *no* reading of
>any records prior to that point.
>
That sounds absurd.  So if a block contains 10 records, you want to
be able to read the last 5 with "*no* reading of" the first 5!?
DASD don't work that way.

>My gut feeling is it *cannot* be done - at least not with RECFM=FB.  It
>*might* be possible with RECFM=F, but efficiency would then be so
>compromised it would  probably outweigh any advantage from *true*
>skip-sequential processing.

How about UNIX files with RECFM=FB,FILEDATA=BINARY and using
seek()?  (But that still reads entire blocks into a buffer.)

-- 
gil

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