From the NTP:
You have a choice of routing a call to one of six priorities. Three are high priority and three are low priority (overflow). The high priorities are denoted as 1, 2, and 3. 1 is the highest priority. The low priorities are denoted as 1, 2, and 3 with arrows next to them. You must have at least one high-priority skillset for each CLID, DNIS, and CDN. You can view only one
routing type (CLID, DNIS, or CDN) in the list at a time.