OK, I did my Google search, and couldn't find the answer (for you folks who like to respond "do a google search").
The question has to do with adding custom materials for Cosmos Express. I've created a copy of the SW materials with a different name.
Upon looking at some of the materials already there, I noticed that some have a combination of metric and imperial values. Upon reading the scanty (and very well hidden) information on the subject, it seems you can use any system you want as long as the syntax is right. Cosmos will convert the imperial values to metric prior to solving. Is this true ???
TIA
Mark