With the qualifiers in place, Wikidata can also be used to achieve this, of course, but it seems we are just manually reverse engineering something that should be done at the site of whoever is controlling the ID registration."
Well said, Markus. A most hearty agreement here on my side and one colleagues and I have been trying to raise awareness of for a long time now (http://bit.ly/id-guidance). One of the challenges is that databases are already being asked to do more with less. They can see the utility of such a service to others, but when I've asked DBs before (not naming names), traction has been limp (I've yet to ask Chembl). Sometimes it works out though. For instance, KEGG used to have 12 different type-specific URLs, corresponding to:
Thankfully, they've collapsed those to a single URL pattern.
The databases that find it the toughest are not those who simply don't embed typing, but rather those that don't embed typing AND ALSO have local identifiers that would otherwise collide. For instance, a prominent bio database is in this boat (not naming names) and would like to make things better but it is hard and messy due to the collisions.
FYI 345 of the 560+ records in the identifiers.org corpus are type-specific at the level of identifiers.org's namespace; these roll up to ~300 providers. The question though is what WikiData is trying to accomplish. Say you encounter the chembl ID CHEMBL308052
do you need to retrieve the type of the entity for reasons other than determining what URL to use?
How are you representing entity labels / IDs to users?