In JavaScript, you can use 32 valid groups (Math.pow(2,0) up to Math.pow(2,31)). However, group Math.pow(2,0) won't collide with any other shape group, and group Math.pow(2,31) will collide with all other groups.
Doesn't it mean to say that -1 (all 1 bits) will collide with all other masks?
The collision filtering wiki says:
Doesn't it mean to say that
-1
(all 1 bits) will collide with all other masks?