We have our Progress 10.0B05 database set up as UTF-8 to accomodate for European and Chinese characters.
MFG/Pro programs are compiled with CPINTERNAL: undefined CPCOLL: basic CPRCODEOUT: undefined CPSTREAM: undefined.
When the client connects, it uses a parameter (.pf) file with a line to set the correct codepage, e.g.
-cprcodeout undefined -cpinternal iso8859-1 -cpstream iso8859-1 -cpcoll basic -cpcase basic -yy 1920
(for iso8859 codepage)
-cprcodeout undefined -cpinternal GB2312 -cpstream GB2312 -cpcoll basic -cpcase basic -yy 1920
(for GB2312 codepage)
I believe that GB2312 is for simplified Chinese. For traditional Chinese you must find the right codepage.
In the case of mixed codepages in one database, you must limit the places where users may enter data using special characters or you will have problems when dumping and loading your data (one of those once-a-year procedures).