For operators supporting a list of parameters (pm, within), it would be very useful to allow to choose the delimiter.
For example, there is no way to use @pm with the string "a b c".
Remark: "a|20|b|20|c" does not work, which is for me a bug.

I propose to use the first non-alphanumeric character after @pm as a separator.
Ex. using / as separator: @pm/Sharepoint Active-X Upload Control
Pipe (|) should probably be refused because of the snort syntax.