WorksheetFunction.IsNonText Method (Excel)
Checks the type of value and returns TRUE or FALSE depending if the value refers to any item that is not text. (Note that this function returns TRUE if value refers to a blank cell.)
expression A variable that represents a WorksheetFunction object.
Value - the value you want tested. Value can be a blank (empty cell), error, logical, text, number, or reference value, or a name referring to any of these, that you want to test.
The value arguments of the IS functions are not converted. For example, in most other functions where a number is required, the text value "19" is converted to the number 19. However, in the formula ISNUMBER("19"), "19" is not converted from a text value, and the ISNUMBER function returns FALSE.
The IS functions are useful in formulas for testing the outcome of a calculation. When combined with the IF function, they provide a method for locating errors in formulas (see the following examples).