In line with Jon Postel's robustness principle:
Schema checks only syntactic constraints, no semantic or taxonomy checks are done.
When IDEA event passes strict schema, warning schema may be applied. Do not use this schema as strict check, but only as a guide to point out possible errors. Schema for example contains full taxonomies, various recommended formats and range checks and also shows as an error when unknown key is used (which is not itself error in IDEA) to point out possible typos.
The repository with IDEA schema and auxiliary tools
git clone https://homeproj.cesnet.cz/git/idea.git/