Thanks @Tigerfell for starting with the case studies, this is a good start. In the end I’d like to have a list of criteria that can be applied to these cases, to make decisions more objective. Naturally however, the criteria for keeping and those for deleting will always have some grey area between them, whereever the threshold is set.
In general, I see the threshold for deletion quite high. OSM lives from the community discussing its changes, and this discussion is expressed in the history of the communication channels. We do keep archives of mailing lists for example, and nobody sits there and weeds out mails that are not relevant to the topic. Equally, the history of wiki pages is an elementary element for transparency, and to understand reasons for decisions and developments. This particularly true for proposals.
So I’d like to start with an incomplete draft for both lists.
- Typo pages, e.g. a page was started with a misspelling in the title, the page has been moved to the correct one. The remaining redirect stub can be deleted.
- Spam unrelated to OSM
- Violations of people’s privacy / data protection rights
- Draft pages on request of the original author, that have not attracted discussion from other users
- Pages that are contrary to basic principles in OSM (e.g. proposing to severely violating copyright, or Good practice). However, if this violation of principles is more subtle and therefore being discussed or disputed, that is a discussion to preserve.
- Utter nonsense (needs further definition, maybe the bullet above is one)
- Proposals that only mention a tag, that is not being used, without describing/explaining its meaning
- Proposals with a vote
- Proposals for tags that are being used, even without a voting process
- Proposals that serve as a documentation for a tag, even if it is not widely used. This should prevent that a tag is being used for a different purpose later. Feel free to add a taginfo counter to such page.
- Proposals that attracted other users who contributed to the page or its discussion. Feel free to add deep-red boxes about the proposal being abandoned or the tag being used inconsistently.
- Proposals independent of their age, i.e. age should not be a criterion. OSM itself is just 15yo.
- Pages linked from other pages