Max, I've answered on forum. There is Content Assist of WTP in JSP editor for tag names. And it needs TLDs. Our CA is used only for attribute values. In XHTML (for facelets) we use our CA (based on our knowledgebase) for tags, attributes and values. So TLDs are not used. We parse unknown TLD only when user drops some tag from Palette. If user wants to have CA for unknown tag lib within facelet page then he should import TLD into Palette and DnD any tag to xhtml. In that moment we try to find TLD then parse it and register it in our knowledgebase. We need it to open our window where user can set attributes values during DnD. But after that our CA is able to use parsed TLD as well. Such TLDs are specials for our KB plugin and we check any changes of it. If user chenged it then we reparse it. Preinstalled TLD (like JSF core, Richfaces, ...) are static for our KB. But as I mentioned it could be problem for facelet pages only. For JSP WTP uses real TLDs from projects.