On Fri, 5 Oct 2012 17:51:13 -0400, Shmuel Metz (Seymour J.) wrote: >on 10/04/2012 at 11:38 AM, Paul Gilmartin said: > >>Or, the OS can prohibit the occurrence of boundary values, and the >>programmer need never be concerned with them. > >No, the OS can prohibit the occurrence of boundary values, and the >programmer who needs them must design a workaround. > Sarcasm overlooked? Implication of infinite regression overlooked?
On Fri, 5 Oct 2012 18:01:49 -0400, Shmuel Metz (Seymour J.) wrote: > on 10/04/2012 at 03:51 PM, Paul Gilmartin said: > >>Was the null segment in VBS invented (partly) to deal with the >>problem of noise record processing on tapes? > >No The lower limit is higher when going to tape. > I understand it's 18 (We can redo the arithmetic below if that's wrong). Suppose I have just one byte of data to write in the last block of a tape, RECFM=VBS. I can write: BDW 4 bytes RDW 4 bytes data 1 byte null segment 9 bytes, for a total of 18, satisfying the requirement. (Or a 100-byte null segment , if the allowed minimum is 109. And I still find it strange that RECFM=VB allows a logical record with data length of 0, but for RECFM=VBS, there is no way to construct a logical record with data length of 0. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
