Last updated: 12 Jul 1999
A calculated field will not appear in the join dialog if it uses fields from more than one database (.dbf) file or if it includes summary functions. Note that using a calculate field in a join may result in substantially decreased database performance.
A work around in situations in which you cannot get a calculated field to appear in a dialog box (join, export, etc...) is to create another field and set the value of that field to the calculated field using a macro.
Also see article 'looping macros'