how to include all forums in f=forumid

[emath]

hey all

ive a mode which add some extra fields to threads,

any way, it has an option to filter the threads by field

for e.g http://www.emath.co.il/forums/forumd...=11&field2=336

all i want is to know, what can i put instead of 11 that it will filter the threads from all the forums ?

i tried * or space or just to put nothing,

either 4,5,6,7,19 (if i write all the forums id) doesnt work...

any ideas?