We provide one module for the Thread prefixes in openx.
This will help you, if you want to set prefix in your thread.
This modification allows the users to choose a thread prefix for each thread.
This will provide a list of prefix beside the title while posting.
You can select an appropriate prefix from a list beside the title while posting a new thread.
For example: ‘Help’, ‘Problem’, ‘Search’ etc.
for more details:
http://www.adservermods.com/openxmods/Thread-Prefixes/prod_1274.html