Name syntax rules:
The Name string must begin with a text character, not a number, and consists of adjacent characters.
Two words can be joined with an underscore (_), for example, to enter the Name “Excel Book”, you should type Excel_Book.
You cannot use a Name that could otherwise be confused as a cell reference, for example, A1 or IS2002, as these are already cell references.
There is no limit on the number of Names you can define.
Be sure to define unique Names for a specific workbook. Defining Names that resemble Names in other sheets will only complicate your work.
Screenshot // Range Name Syntax