Hey, Dr. Koch,
Ahh, okay, .sas7bcat files. A .sas7bcat file is a SAS Catalog, and, yes, catalogs are where user-defined formats are stored (among other things).
You cannot open .sas7bcat files in JMP. If you want to use the user-defined formats stored in catalogs in JMP, you will need to connect to a SAS server from JMP and access the data that way, instead of using File > Open. JMP has the ability to convert SAS user-defined formats to JMP value labels when connected to SAS.
HTH,
Eric