https://community.graphisoft.com/t5/Libraries-objects/Unknown-Subtype/m-p/273253#M1969 Just found the answer. Reverting to &lt;Unknown Subtype&gt; occurs when you have a part with the subtype you are editing nominated. From what I can tell, if you are going to edit a subtype, make sure all other parts you are editing are closed. Tue, 19 Nov 2019 13:55:35 GMT wilson83 2019-11-19T13:55:35Z https://community.graphisoft.com/t5/Libraries-objects/Unknown-Subtype/m-p/273252#M1968 <DIV class="actalk-migrated-content"><T>I have created a subtype and applied the subtype to several files as a template. As I develop my part(s) I want to be able to edit the subtype to then roll out any new parameters across all parts. When I add a parameter to the subtype file and save, all the other parts using the subtype revert to &lt;Unknown Subtype&gt;. How can I adjust a subtype without the other parts reverting to unknown?</T></DIV> Tue, 19 Nov 2019 13:42:53 GMT https://community.graphisoft.com/t5/Libraries-objects/Unknown-Subtype/m-p/273252#M1968 wilson83 2019-11-19T13:42:53Z https://community.graphisoft.com/t5/Libraries-objects/Unknown-Subtype/m-p/273253#M1969 Just found the answer. Reverting to &lt;Unknown Subtype&gt; occurs when you have a part with the subtype you are editing nominated. From what I can tell, if you are going to edit a subtype, make sure all other parts you are editing are closed. Tue, 19 Nov 2019 13:55:35 GMT https://community.graphisoft.com/t5/Libraries-objects/Unknown-Subtype/m-p/273253#M1969 wilson83 2019-11-19T13:55:35Z