>the command
>? file("C:\d\intrin\com\BlankEx")
>returns .f.

You didn't specify a file extension

? file("C:\d\intrin\com\BlankEx.dbf")

>
>and this does not help
>If USED("C:\d\intrin\com\BlankEx")
>Select("C:\d\intrin\com\BlankEx")
>USE
>CLOSE all
>endif

Both USED() and SELECT in the code above expect a work area alias not the file name.