Felix,
You have several possibilities to satisfy your needs.
First you need to be sure which data set name is displayed into the view.
These SMF data sets into the DTOC4SYS view are probably named BNB1.MAN1.DATA for example.
So that means you need to code:
1) "Dataset-Name" INCL BNB1.MAN?.DATA AND "Used" < 10
2) For specific data sets and not all of them you can code
("Dataset-Name" INCL BNB1.MANX.DATA OR Dataset-Name" INCL BNB1.MANY.DATA) AND "Used" < 10
This will work too.
If you do not succeed please open a case so I can assist you directly.
Regards,
Pierre