>>>>> "G" == Gavin Sinclair <gsinclair / soyabean.com.au> writes:

G> When I discovered this some time ago, I wondered deeply what might be occupying
G> id #s 2, 4, 6, ...

pigeon% ruby -e '[false, true, nil].each {|i| p i.id}'
0
2
4
pigeon% 

 6 is for Qundef (internal use)

G> I'm surprised that numbers that high have a predictable ID, as if they're
G> predefined.

 Look at rb_obj_id() in object.c


Guy Decoux