Do we know firsthand how many IATI identifiers contain special characters, seeing I don’t have those numbers in front of me.
From API (OIPA) perspective this has been an ongoing issue for years now. Non URL/URI compliance does in many cases require a custom approach from our perspective. Seeing how others may have a different approach as well, this does not add to interoperability if we for example were to align different systems in the IATI network.
Basically the issue is two-fold: an IATI org. identifier can contain special character plus the additional identifier may contain special characters as well.
We would prefer this to be solved at the root of the chain -the standard itself- and not anywhere else.