hello

i need a hand on a global. here the structure of a site:


what i'd like the global to do is to add a link to the previous and next category (previous and next in the alphabetic order) on the category pages:




for examples:

on subcat02 pages:
previous category would link to subcat01
next category would link to subcat03


on subcat01 pages:
previous category would link to subcat12 (the last cat)
next category would link to subcat02


thanks for your time and help

jerome