Configuration index square planar systems

The configuration index for a square planar system is placed after the polyhedral symbol (SP-4). It is the single digit which is the priority number for the ligating atom trans to the ligating atom of priority number 1, i.e. the priority number of the ligating atom trans to the most preferred ligating atom. 

Square planar coordination systems (SP-Jt The configuration index is a single digit which b the priority number Tor the ligating atom irons to the ligating atom of priority number l.33... 

---