You can use data validation to limit what a user can type in a cell. The
data validation can refer to a list on a worksheet, or to a list that
you type in the data validation dialog box. There are instructions here
for using a list on the worksheet:

http://www.contextures.com/xlDataVal01.html

Note: if you type the list in the data validation dialog box, it is case
sensitive. For example, if your list is "y,n", users will be able to
enter lower case y or n, but not upper case Y or N.

renee wrote:
I need to know how to set up data validation that only allows the user to
type y or n in a cell.


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Debra Dalgleish
Excel FAQ, Tips & Book List
http://www.contextures.com/tiptech.html