question about to_tsvector and to_tsquery

Is there any more information on exactly how to_tsquery and to_tsvector are
supposed to work?

select to_tsvector('simple', '1.b') gives '1':1 'b':2
but
select to_tsvector('simple', '1.bb') gives '1.bb':1

select to_tsquery('simple', '1.b:*') gives '1':* & 'b':*
but
select to_tsquery('simple', '1.bb:*') gives '1.bb':*

Regards,
Martin

--
Martin Norbäck Olivers
IT-konsult, Masara AB
Telefon: +46 703 22 70 12
E-post: martin(at)norpan(dot)org
Kärrhöksvägen 4
656 72 Skattkärr