[Zope] Meaning of sequence-index-{variable}

[Luciano Ramalho]

I'm writing a Zope Quick Reference, and am stuck trying to figure out  
the meaning and use of this variable, one of the many available inside  
a dtml-in loop.

All editions of the Zope Book (and every other Zope book I know about)  
pretty much say the same thing:

sequence-index-{variable}: The index of a variable of the current item.

You are supposed to replace {variable} with some attribute of your  
current item. I've tried that with no success (although I've managed to  
test every other documented sequence-* variable).

You can check the official docs here (but they haven't helped me):

http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/ 
AppendixA.stx

Reading the source seemed non-trivial in this case, so I decided to ask  
after a while (the only relevant module in Zope 2.6.1 seems to be  
DocumentTemplate/DT_InSV.py).

TIA for any help!

--
Luciano