I have requested Alibre include "Reference Dimensions" that will allow you to create a dimension that is not a driving dimension, yet is included in the Equation Editor, and hence the BOM.
A simple checkbox in the Dimension Properties for that dimension, that will include the dimension in the Equation Editor, so you can name it and have it be included in your BOM.
That would greatly increase the usefulness of Alibre in outputting dimensions to Cutlists, via the BOM. Any dimension that is created by referencing another part currently can not be used,
whether in a part or assembly. Projected Geometry is useless if you need to output the dimension via the BOM. Hopefully if enough people mention this problem, we could get such a feature included.