Because data sessions control the scope of certain SET commands, you can use private data sessions to establish custom SET command settings within a single session of Visual FoxPro.
For example, the SET EXACT command, which controls the rules used when comparing character strings of different lengths, is scoped to the current data session. The default setting for SET EXACT is off which specifies that, to be equivalent, expressions must match, character for character, until the end of the expressions on the right side is reached. You might want to enable "fuzzy" or equivalent searches by leaving SET EXACT set to OFF for the default data session; however, your application might contain a specific form that requires exact matches. You could set the DataSession property for the form requiring exact matches to 2, to enable private data sessions, and then SET EXACT to ON for that form. By issuing a SET command only for the form using private data sessions, you preserve the global Visual FoxPro session settings while enabling customized session settings for a specific form.