[Zope] emulate a sequence

[Yuri]

Hi!

 I need a field in zope object which act as a sequence. I mean every 
time I create an object, the value is the previous sequence value of the 
last object created + 1.

 also I need to browse the objects by sequence (from the object 1 to the 
last, by the sequence number)

 I think I need a catalog FieldIndex to store the sequence for searches, 
a property in the object.

 Can I use the catalog to retrieve the max value of the index, so when I 
create the object, I just add 1 and store it in the property?

 TIA