The SDXInternalVersion and SDxSource properties are set on the Schema and Admin objects when they are delivered by the upgrade process. For example, if a new method is delivered in Update 19 then the SDXInternalVersion is set to the version 10.00.19.xxxx. If the same method is then delivered in Update 20, then the method version is still set to first version 10.00.19.xxxx that was delivered.
The SDXInternalVersion and SDxSource properties are set on the Schema and Admin objects irrespective of if they are new
or modified.