megatronx
"condition: ENTRY IS VALID" could check if the target row,col is valid. For example , if the (col, row) = (Gun, Bullet) is not in the table, it will return false.
"condition:KEY IN COL/ condition:ROW" is similar with "condition: ENTRY IS VALID". For example , if "Gun" is in col , it will return true.
condition: ENTRY (Gun, Bullet) IS VALID = (condition:KEY "Gun" IN COL) and (condition:KEY "Bullet" IN ROW)