I have seen discussions about what tag to use since I first joined OSM and it's not always easy to understand. Some things seem obvious like tagging a road. It's a highway right, so highway= ... ? Residential is fairly easy (but is it a living_street), but is a substantial road a trunk road or a primary, or even a secondary? Is a small road a service road, a track, an unclassified or even a path?
How do I tag a church? Apparently it's not a church, it's a place or worship, so then it needs an extra religion tag to differentiate churches from temples from synagogues etc. Why not just tag it a church or a temple?
Areas of land are unfathomable. Some get the landuse tag, i.e. how the land is used such as retail or commercial. That makes sense, but then along comes landuse=grass. Not 'used for grazing' or 'used to suppress weeds', just landuse=grass. Hmmm, does that work?
So it seems that somewhere in the past a plan was devised to sort this out: an approval process. New tags would be proposed, discussed and commented upon and then voted on, so tags would be approved for use. Approved tags? What's that all about? There are no approved tags, anyone can use any tag that suits their purpose. That's at the core of OSM and part of what makes OSM so successful.
Imagine what would happen if I couldn't use any tag I want to. Picture the scene: I come across something that is not in the list of approved tags. I want to add it to the map. I have two choices, 1) add it as something else that is in the approved list but that is not what I have seen or 2) I can walk on by and not add it until it is in the approved list.
Both of these are stupid: option 1) will show up as the wrong thing until the tag is approved. What if the tag is not approved? Will I remember to remove it? How will I feel about removing my hard-won object?
Option 2) is even worse. The object will not get into the map database. So not only will no one looking at the map or database know it is there, no one will know there is such a thing waiting to be added, so when (if) the tag is proposed no one will know how many of them there are waiting for the tag. Will I go back and add it to the database after the tag has been approved? Somehow I doubt it, more likely I would be fed up with the bureaucracy of the process and will have left the project to give my time to someone else.
Then there's the thorny question of who should be the one to approve these new tags? No one owns OSM, so there's no one to appoint an approver. How do I know what it is you are interested in or what you want the map to be about? I don't so doesn't that rule me out from approving your tags? That effectively rules everyone out from being the approver since no one can understand everyone's motivations, so next you need a committee to try to cover more interests. How big will the committee need to be? Who sits on the committee? Am I allowed to vote someone on/off it? Why? What gives me a vote? Do I get a vote because I have been in OSM for six days? Six months? What if I have only changed a single road name in that time? So maybe I get a vote because I've added a thousand nodes. I could just add loads of nodes into existing roads just to get my vote. Can I buy a vote in return for a donation of ten dollars? What about 10,000 dollars?
So even if some sort of committee gets formed, how often do they meet? Will they need to get advice from other experts? So how long will it take to get a tag approved? When they do decide to turn down a tag will there be some sort of appeal process? What if that is challenged by a rich company that wants a tag approved and who has a large legal team?
How will people be bound by any of this? Clearly they will have to agree to this, so as well as signing up to a licence for the data, they will have to agree to be bound by the Approvals Committee. How many people will agree to that?!?
So the answer is simple. Allow people to use any tag they like and allow a process of natural selection to merge disparate tags together as a consensus develops. Publish a list of tags that are widely used based on statistics. A description of how people have chosen to use it would help other people decide if they want to use it too. A list of the tags supported by some of the main data consumers such as renderers and routers would help too.
If this the right way to do it, then why does the approval process exist? A very good question. I don't think it should not be there at all. Removing the process would remove the right of passage of creating a tag. It would stop the stupidity of someone creating a tag, getting it through the voting process by a few people voting to approve it and then claiming it is an approved tag and demanding it gets rendered even though it has hardly ever been used. It stops people voting for or against a new tag even though they have not used it, have no knowledge about the subject and only voted because someone invited them to do so on a mailing list.
So I do sometimes struggle to find the best tag to use, but I'm relaxed about that. I am not at all happy about the phoney, abused and irrelevant tag-approval process and I would like it to end now.