Caroline,
CONVERT can only process entire records. One record in corresponds to one record out. The most you can do is truncate or pad. As soon as you need anything that cuts and/or merges records, you need to write a program.
As Hein suggests, SET FILE/ATTR may fix the file (perhaps it was FTPed as BINARY instead of ASCII?).
If not, here's some DCL that might help. It treats the input file as a stream, cuts it into fixed length records and writes them to a stream_lf output file.
$ IF p1.EQS."" THEN INQUIRE p1 "Input file"
$ IF p2.EQS."" THEN INQUIRE p2 "Output file"
$ IF p3.EQS."" THEN INQUIRE p3 "Output record length"
$
$ ON WARNING THEN GOTO Cleanup
$ ON CONTROL_Y THEN GOTO Cleanup
$ OPEN/READ in 'p1'
$ CREATE/FDL=SYS$INPUT 'p2'
RECORD
FORMAT STREAM_LF
$ OPEN/APPEND out 'p2'
$ EOF="false"
$ READ/END=Cleanup in buffer
$ loop:
$ IF F$LENGTH(buffer).LT.p3
$ THEN
$ GOSUB more
$ IF eof THEN WRITE out buffer
$ ELSE
$ line=F$EXTRACT(0,p3,buffer)
$ buffer=buffer-line
$ WRITE out line
$ ENDIF
$ IF .NOT.eof THEN GOTO loop
$
$
$ More:
$ READ/END=eoin in line
$ buffer=buffer+line
$ RETURN
$ eoin:
$ eof="TRUE"
$ RETURN
$
$ Cleanup: SET NOON
$ CLOSE in
$ CLOSE out
$ EXIT
A crucible of informative mistakes
