The space is actually the key to separating multiple patterns. For instance, in the following, the Blast SOP deletes points that match the patterns v@P.y<0, v@P.x<0 and point number 0. The space between them allows it to be read as 3 separate patterns.

The following Group Syntax section of the SideFX docs some other helpful syntax options: https://www.sidefx.com/docs/houdini/model/groups.html#manual