Strange Magnetic Tapes can be analyzed with the MTANAL System procedure:
MTANAL MAG1: (or MAG2:)
To copy files to disk from a magnetic tape which you have just `MTANAL-ed':
COPY MAG1:,FILE.EXT,RECL=xx,NF=1,SKIP=yy
The default skip is yy=0, but specifying SKIP=0 will result in an error status. In order to copy the whole tape, specify NF=ALL.