Hmm... interesting idea, although I have serious doubts about the effectiveness of any centralized system like this.
In short: it won't work because most addonmakers won't use it.Perhaps some, or even most, popular/large addon teams will use it properly. But the hundreds of small, single-man addons that are released every damn month will NOT, in general. And, as mentioned, the non-english speaking community will likely be out of reach as well.
OFPEC tags are a great example. Been around since 2002, yet we still see addons released without any sort of tag at all. Or we see addons that have improper/unregistered OFPEC tags, such as
bn880's tracers (uses 2-letter, unregistered OFPEC tag).
However, even more revealing is the
OFPEC tags listing. This is a single, already existing, centralized location for addonmakers to list their addons. Yet few, if any, addonmakers bother to update the information here. Check out the
Finnish Defence Forces tag listing, which says they haven't released anything at all. (For the record,
my listing, which has at least been updated in the past, isn't current either)
I'd say that OFPEC tags are still successful, however. The reason: most addonmakers are aware of the reason
why they exist, and so they include something like the tag system in their addons (your improper 2-letter tag is a good example; it gets the job done, even if it isn't 'according to standard' or 'registered').
Basically, the 'spirit' of the tags is alive and kicking, even if the centralized database is cold and dead. The problem I see with your idea, is that there is NOTHING to live on if the database part doesn't end up working.
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The answer, as I see it, lies in the sites that
distribute addons. OFP.info has got to be the largest and most popular of these sites. Yet, in some ways it is a nightmare of organization. There are no descriptions for addons... addons are sometimes contained in their 'news archives', and sometimes in their addons section... their addons section is a pain to navigate thru... etc etc ad nauseam.
Contrast this to the
OFPEC addons depot, which in many ways is much better organized. Addons are organized into more catagories... you can see how many are contained in each catagory... you can change the display of each catagory (according to release date, author, etc)... addons have both author descriptions, and reviews... each entry has info like author website/email, links to other addons by that author, date released, version, and so on...
In short, it is much easier to find the right addon on OFPEC then on ofp.info. The only problem, obviously, is that OFPEC's addon collection is small and outdated, whereas ofp.info is about the largest and up-to-date there is.
So I think effort would be best spent getting ofp.info to organize their addons better, while getting OFPEC to update their addon depot. Perhaps other sites will follow suit.
Just my 2 cents.
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APPENDUM
Part of the problem, obviously, also lies on the addonmaker's shoulders themselves. Terrible readme's are possibly the biggest problem. Many don't include the version of the addon, for example. Often there is no reason to save the readme after downloading, since it contains no useful info. (Later on, if I download a mission that uses that addon, I would have no way of knowing if I already have the proper version.)
If the community as a whole would be critical about the readme (as they are about the rest of the addon), then the quality of readmes WOULD improve, as a whole.
The same goes for mission readmes. Authors need to include the required version of the addon, multiple links to the addon, the filesize, etc, so that players can be sure they downloaded the right one.