Need a Data Validation sort of thing which allows on 3 different characters in the whole selected cells

[Amit Punia]

Hi, I need a data validation sort of a thing where a set of cells only takes some specific characters/alphabets like "A", "B", or "C" only. If the user is selecting anything else apart from this then it doesn't allow them to do so.

Don't need a data validation with drop down menu.

E.g. If in Cells A1:D5 I need to allow the users to type only alphabet "A", "B" or "C". If user tries to type anything else apart from this, then the excel show them error or doesn't let them type anything apart from these 3 characters/alphabets. Don't need a data validation with drop down menu.

Thanks in advance.

 

[Peter Bartholomew]

= AND( ISNUMBER( SEARCH( letters, string ) ) )