>I an not sure if I do not understand the set default command or if this is a bug.
>
>I determine the default directory and assign it to a variable, i.e
> m.gcDefDir = SUBSTR(SYS(16,0),1,RAT('\',SYS(16,0)))
> i.e 'c:\defdir'
>Then I a set the default directory using the command
> set default to m.gcDefDir
>The command
> ? set("default)
>returns "C:" instead of "c:\defdir". Is that correct? If not what am I doing wrong?

First, you can use justpath() function. Second you've to enclose m.gcDefDir variable in the parenthesis to tell VFP that's Name Expression.

m.gcDefDir = JUSTPATH(SYS(16,0))
set default to (m.gcDefDir)
? FULPATH("")