What Does It Do?
This function shows TRUE if given a cell address, or FALSE for any other type of value. Its a bit of an odd one, and is normally used in macros rather than on the worksheet.

Syntax
=ISREF(ValueToTest)
The ValueToTest can be any type of data, but when used on the worksheet, it cannot be a reference to the contents of another cell, as the reference will itself be evaluated by the function.

Formatting
No special formatting is needed.