[Zope] How to prime a selection?

[Jean Jordaan]

Hi all

I'm making a document class for a warehouse of papers.
It's based on ZCatalogAware and ObjectManager (to wrap
mainly PDFs and DOCs), and has fields:

  title   (string type)
  origin  (string type)
  format  No value for format_value.  
  type    No value for type_value.  

"format" and "type" are selections -- 

1. where do I supply their initial values (filling in 
   'format_value' and 'type_value')?
2. is it possible to let a field offer presets and 
   previously entered values, but to allow users to 
   add new ones, which are remembered and offered to 
   subsequent users?

A RTFM-type answer to question 1. is perfectly OK, though a 
page reference would be sorely appreciated.

-- 
jean