@@ -146,6 +146,10 @@ gmql_join <- function(left_data, right_data, genometric_predicate, joinBy,

         if(!is.character(reg_attributes))

             stop("metadata: no valid input")

+        ouput <- toupper(region_output)

+        if(ouput %in% c("CAT","INT"))

+            stop("reg_attributes is defined: output cannot be INT or CAT")

+        

         reg_attributes <- reg_attributes[!reg_attributes %in% ""]

         reg_attributes <- reg_attributes[!duplicated(reg_attributes)]