The output of mfdbcatc with the command below, generated the KSDS file with "type=seq" :
 
mfdbcatc -u -c /home/junf/projects/jcltest/data/catalog.dat -fs $DATADIR -fd 'sql://DB2SVRJUN/VSAMDATA/?type=folder;folder=/data' -v

The output of mfdbcatc, deployfile, generated “type=seq” for KSDS file MF.EMPFILE.DAT:

data add /home/junf/projects/jcltest/data/files/MF.EMPFILE.DAT sql://DB2SVRJUN/VSAMDATA/MF.EMPFILE.DAT?folder=/data/files;type=seq;reclen=0006,0116
data add /home/junf/projects/jcltest/data/files/MF.EMPFILE.DAT sql://DB2SVRJUN/VSAMDATA/MF.EMPFILE.DAT?folder=/data/files;type=seq;reclen=0006,0116
data add /home/junf/projects/jcltest/data/files/MF.EMPFILE.DAT sql://DB2SVRJUN/VSAMDATA/MF.EMPFILE.DAT?folder=/data/files;type=seq;reclen=0006,0116

Full article: https://portal.microfocus.com/s/article/KM000010689