Cried a voice from the wilderness:
 
As part of a data conversion project, we are trying to create a tape that an
IBM MVS
system can read.  Tape specs call for a labelled tape written with variable
length
records, e.g. 77 to 840 bytes.
 
We have created a variable-length flat file on our 3000, shown as follows:
 
        :FILE SIG080T1;REC=-840,38,V,ASCII;...
 
 
which the file system (MPE/iX C.50.00) displays in LISTF as:
 
        FILENAME  CODE  ------------LOGICAL RECORD-----------  ----SPACE----
                  SIZE  TYP        EOF      LIMIT R/B  SECTORS #X MX
 
SIG080T1        31994B  VA         732     100000   1     2048  4  *
 
 
This file is then FCOPYed to an IBM-labelled tape on an HP7980XP specified as
follows:
 
        :FILE T=SIGCONV;DEV=TAPE;REC=-840,38,V,ASCII;LABEL=001900,IBM;DEN=6250
        :FCOPY FROM=SIG080T1;TO=*T;EBCDICOUT
 
 
On the receiving end, the IBM'ers say that they can read only one record per
block
which they show as 31998 bytes.
 
Questions and constraints:
 
        1.  What do we need to do to create a variable-length record that an IBM
        can reliably read?
 
        2.  Is it possible that the IBM software is actually deblocking the data
        and the operators don't know it?
 
        3.  Have any of you done something like this?  I know some people out
        there (Jeff?) have to coexist with IBM hardware, and have done so for
        some time.
 
        4.  The tape file must be variable-record, and FTP transfer isn't an option
        open to us with these people.
 
I am humbly grateful for any aid you can give us.  This one has us stumped.
 
 
--Jim