Welcome to TagDoc,
In contrast to the OpenStreetMap Wiki, TagDoc aims to document exclusively the de facto meaning of tags or, in other words: How and with what meaning the tags are used and what they actually substantially tell us about the observable geography of Earth. It tries to provide a qualified assessment of the local knowledge recorded in OpenStreetMap for both data users and mappers, without mixing that with subjective ideas on how tags should be used.
To accomplish that, TagDoc is not open for everyone to edit - it is a curated collection of documentation. Everyone is, however, invited to comment on the documentation of tags here, after logging in with their OpenStreetMap account - see commenting instructions for details.
At the moment, TagDoc is just an experiment I am working on in the limited free time I have available. That is evidently not sustainable to produce and maintain an extensive documentation of all tags in OpenStreetMap - or even those few thousand tags that are known to be used by some project in the OpenStreetMap world. There are different options to overcome this constraint - more details on this can be found on TagDoc:About.
For the moment, the full list of tags documented on TagDoc can be found below - as this list grows it will ultimately be moved somewhere else, of course.