The LDAP schema used by OVD is shipped as several XML files such as schema.core.xml, schema.cosine.xml, schema.inetorperson.xml, schema.nis.xml etc. depending on in which RFC the attribute and object classes are defined.
All changes to these schemas (if any) are always applied to schema.user.xml, so this file contains all the custom attribute types & objetclasses.
Hope this clarifies a bit
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