Mozilla Corp. continues to fine-tune the feature set for the next major update to its Firefox browser, due in the second half of 2007, and on Wednesday posted an updated plan. The Firefox 3 wiki, a list of the planned changes and additions to the next upgrade of the open-source browser, now sports designations that mark features as either "functional" or "non-functional." The latter, although strictly not optional, are more intangible goals, such as "improve usability of Add-On Manager" or "simpler print preview dialog." The former, however, are more concrete, and include to-dos like "support Microsoft CardSpace" and "improve search, retrieval, and startup performance." Among the features currently pegged as must-haves by Mozilla for Firefox 3 are an overhaul of the browser's bookmark system and new identity management tools. Mozilla released an early preview of Firefox 3.0, dubbed "Gran Paradiso Alpha 1," last month. When the previous update to Firefox 2.0 was launched in October, Mozilla said it would roll out a major enhancement about once a year. According to the Firefox 3.0 release plan, however, the company may also consider incremental updates -- Firefox 2.5, for instance -- that act as extension packs to the standard browser. Microsoft also has promised that it will update its Internet Explorer browser every 18 to 24 months, a much shorter cycle than the 50 months between IE 6 and IE 7. No responsibility can be taken for the content of external Internet sites.