Here's a method you can use to check if a text value is actually a number. This is useful if you are parsing a text file containing a variation of character of numerical strings.

  ` checks if all characters are numerical characters

C_TEXT($1;$char)
C_LONGINT($i)
C_BOOLEAN($isChar)

$isChar:=False

For ($i;1;Length($1))
  If ($isChar)
    $i:=Length($1)
  Else
    $char:=Substring($1;$i;1)
    If ((Ascii($char)<48) | (Ascii($char)>57))
     $isChar:=True
    End if
  End if
End for

  ` is it a character string?
$0:=Not($isChar)