Paul Gilmartin wrote: <begin extract> 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. <end extract>
It is not that there is no way. I can think of one, and I suspect that you have thought of one, It is that the tradition of FORTRAN green words for data-directed I/O---It dates back to tape I/O for Backus's first FORTRAN compiler for the IBM 704---is still strong and pervasive. --jg On 10/5/12, Paul Gilmartin <paulgboul...@aim.com> wrote: > 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 > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
