The compilations system is built around auto-generated cards (using levels to connect all the data). 

If a compilation has to be generated by Major Tag and the cards included in it have been created using both levels of equipment (Major Tags and Tagged Equipment Units) we recommend choosing Major Tag level for the compilation doc codes.

And even if the Card List has been built entirely with manual cards it is important to use auto-generated cards for the compilations in order to cross the hierarchy of major tags/equipment tag and make sure that all cards have been included in the applicable Major Tag compilation.

There is also the option to choose manual cards for compilations. But if manual level is selected for the compilations, the books will include only the cards linked to Major Tag units and will exclude all the cards which have been linked to specific Tagged Equipment Units.