Plg_kunenadiscuss is a project mainly written in ..., it's free.
Discussion/Comment plugin for Kunena on Joomla
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Kunena Discuss Plugin README
PLEASE READ THIS ENTIRE FILE BEFORE INSTALLING Kunena Discuss @kunenaversion@!
Kunena Discuss enables your site visitors to discuss your content articles in designated forum categories.
Requirements: Joomla 1.5, Kunena Forum 1.6