about GiST indexes

[Sergej Galkin <sergej(dot)galkin(at)gmail(dot)com>]

Hello to all,
I'm a young programmer student, and I would like to realize TPR-index on
Postgresql system. Of course I want to use GiST template, rather than
writing core :)
I have some questions, and I would be very grateful if anybody answers my
question.
1) where could I know the prototypes of such functions as union, pentaly and
etc. And to read more detally than in PostgreSql documentation ?
2) How could I save in index structure  index created time, and to get this
value when I envoking such procedures such as union, penalty, pick split ?

Best regards,
Sergej Galkin