I have a question about string variables in Epidata analysis. 

I have a string variable that has over 20 categories for diseases but there is also some missing data in the form of a blank cell or a "." in the cell. Epidata isn't recognizing those cells as missing and I would like to exclude the missing values from my analysis.  Is there a easy way to do this, besides going through and selecting the 18 of the 20 categories that I want to include?

Thanks,

Kate