I have ArcPad10 installed on a Trimble Juno. I tried to use a geodatabase with a feature class set up with domains and subtypes for field data collection, but, I learned quickly that ArcPad10 doesn't recognize a geodatabase... only shapefiles.
I understand that an *.apl file (part of a shapefile package) is used in arcpad10 to constrain data editing, or create forms. Do you need ArcStudio to create an apl file? What is the structure of an apl file? Can you write your own?