VALONEOF
Use @VALONEOF to compare a field or string to a list of values. If the field is in the list, 1 is returned, otherwise 0 is returned.
                  
Syntax
@VALONEOF (expression,value[,value] [, ...])
Example
If STATE is CA or NY, this expression returns "COAST".
                  
@IF (@VALONEOF (STATE, "CA", "NY"), "COAST", "MIDDLE")