Problem:

the .bat file pasted

....1) creates an empty Line sequential file ( echo >fils.dat )

....2) creates an INDexed file using MF REBUILD conversion features

Resolution:

Extract of the .bat file:

echo >fils.dat

rebuild FILS.dat,FIINDf.dat /o:lseq,ind /k:1 10 /r:f50

rebuild FILS.dat,FIINDv.dat /o:lseq,ind /k:1 10 /r:v10-50

dir fiIND*.*