I want to create a user defined subclass within my package symbol and have it mirror with the package. How do I do this ?? You will notice that Allegro has standard class/subclass names such as ASSEMBLY_TOP and ASSEMBLY_BOTTOM. The _TOP and _BOTTOM are the keywords to making this happen. You may create a user defined subclass under the PACKAGE GEOMETRY class, using Setup – Subclasses… such as MYCLASS_TOP . When you place this into a .brd board file, the MYCLASS_TOP subclass will automatically be added to the board database if it does not exist already. In order to mirror the package symbol properly please be aware that you must add the subclass MYCLASS_BOTTOM to the database before performing the mirror command (the first time). If you do not do this, you will get a message in the Allegro output window stating “No match found for subclass name.” In summary, the _TOP and _BOTTOM are the keywords to making this happen. Hope this helps you.
Is Cadence still planning to make the creation of the "_bottom" layers automatic for user defined layers in some future release?
This will be done in the 15.5 release.