The Allegro PCB Editor 16.6 ‘Show Measure’ command now displays results in database and alternate units. Alternate unit display requires the enablement of the user preference variable ‘showmeasure_altunits’. ‘Show Measure’ also supports a measurement between padstacks even if a common layer does not exist. This will be helpful when measuring mask-related geometry to conductor.
Read on for more details …
Open the User Preference Editor as we need to enable the variable for dual units. Setup – User Preference Editor – Display – Element:
Select an alternate unit of your choice; for example ‘millimeters’:
Invoke Display – Measure or use the icon 
then make an adjustment to the find filter that aligns with your intended selection (pins, shapes, etc). Note the dual unit display in the report window:
Measure two elements originating on different layers. For your convenience, there is a soldermask shape just below the Xhatch area:
I look forward to your input on this new capability.
Jerry “GenPart” Grzenia