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 FRE(numeric-expression% | stringexpression$)
 
 Usage Notes
   ■ When a string expression is specified, the FRE function compacts the
     free string space into a single block, then returns the amount of
     available string space.
 
   ■ FRE(-2) returns meaningful values only when a program is executing.
     Values returned by FRE(-2) are not accurate when the function is
     called from the Immediate window, during program tracing, or when
     watching a variable. The unused stack space indicates how much stack
     is needed so that DGROUP can be reclaimed.
 
   ■ If expanded memory is not available, FRE(-3) returns the error message,
     "Feature unavailable."
 
   ■ FRE(-3) is no longer available with compiled programs using overlays.
     If you are running a compiled application using an earlier version of
     Basic expanded-memory overlays, the value returned by FRE(-3) is based
     on the total amount of expanded memory available. (When using overlays,
     you cannot limit the amount of expanded memory used by your program.)
 
   ■ If you are running a program with no forms loaded, FRE(-4) returns the
     error message, "No currently active form."
 
   ■ If you start Visual Basic (VBDOS.EXE) without the /E:n switch, you will
     be using all expanded memory available on your computer.
     See: ◄VBDOS Command-Line Options►
 
   ■ If you start Visual Basic (VBDOS.EXE) with the /E:n switch, you can
     limit the amount of expanded memory available to your program. For
     example, if your computer has 5 MB of expanded memory but you want to
     use only 4MB of expanded memory, you can start Visual Basic with this:
 
         VBDOS /E:4096
 
     If you have specified 4MB of expanded memory as shown above, and then
     you use 2MB of expanded memory in your program, FRE(-3) returns 2048.
 
   ■ You can use the FRE function to approximate the amount of memory taken
     up by a form or controls placed on your form. For example:
 
         SUB Form_Click ()
              Loaded! = FRE(-1)
              UNLOAD Form1
              Unloaded! = FRE(-1)
              SHOW
              PRINT STR$(Unloaded! - Loaded!)
         END SUB
 
     You can write an event procedure similar to the one above to determine
     the amount of memory used by a given control before or after placing
     that control on a form. For example, if:
 
         A = Size, in bytes, of default form with no controls
         B = Size, in bytes, of form with one control
 
     then:
 
         B - A = Amount of memory, in bytes, taken up by the control