It seems to be standard practice (and reccomended in the wiki) to tag former industrial buildings (ie, that clearly look like factories) with “building=industrial”. That seems fairly incomplete to me, as it gives the impression of many areas being full of industry which are actually full of student accomodation, flats, and commercial premises.
It seems to be slightly better with churches as you see “building=church” mixed with “disused:amenity=place_of_worship” and “building:use=x”. Industrial units are more likely to be large and mixed-use, so it’s not really possible to give them a single use, or a former amenity to be disused.
What should be done with them?
Are there further tags for previous industrial use (ie textile mill)
If building:use is too broad a brush for a building that has been internally subdivided you could use something like building:part:use instead.
Unless there is evidence that the previous building use is still visible in person or that it is still referred to as “the old X” by locals then the former use if probably more of a thing for OpenHistocialMap. If evidence of the former use remains then there are lifecycle prefixes like was: and disused: that can be used.
Before getting to building:part= , building:use= can still be for the main use, similar to the logic of building= in a functional aspect. If there are only shops at the bottom floors or small sections, and all flats above or surrounding, it can be =apartments as a new building= would. Furthermore, semicolon multival =apartments;retail could easily be used, as it’s an attribute, not a feature as building= that would cause low-level incompatibilities and complications.
If we’re talking about whole area, mark the polygon with e.g. landuse=residential and/or landuse=retail (even if full of building=industrial)
if we’re talking about specific building, then add to to building=industrial appropriate “usage” tag e.g. amenity=student_accommodation, shop=mall, building:use=* appropriate for whatever purpose they serve nowadays. If one building has been subdivided into different usage, create specific POI nodes inside those buildings (e.g. shop=convenience, amenity=post_office or whatever) or subdivide with building:part=* polygons and put appropriate usage tags on them.
For that specific usage, I don’t know how to tag even currently working textile mill (and thus neither how to tag the old one).
But generally you’d use lifecycle prefix. e.g. if it was man_made=watermill that is no longer functional but has parts of machinery remaining, it would become abandoned:man_made=watermill (along with any other tags that might depict its current use, e.g. it might be tourism=attraction + attraction=historic, or even converted to tourism=museum etc.)
