This directory is indended to store schema files for 3rd-party plugins.

Each schema file should be named NN-description.ldif where NN is a number 00..90.

The schema files from this directory are merged together with the core IPA
schema files during the run of ipa-server-upgrade utility. Therefore, they are
also installed when upgrade happens within the process of ipa-server-install.

The directory is installed as /usr/share/ipa/schema.d and is owned by a
ipa-server-common package. Therefore, a 3rd-party plugin would need to
depend on the ipa-server-common package if it delivers the schema file(s).

You may place your schema files in a subdirectory too, the code that loads
schema files processes recursively all subdirectories of schema.d.