What is the reason to define `P` here?

In this line https://gitlab.esss.lu.se/icshwi/e3ioc-ecmclebtiris/-/blob/master/st.cmd#L111 we define P:

epicsEnvSet("P" ,"LEBT-Iris:Ctrl-ECAT-01")

However, this is never used: all of the references below are of the form

dbLoadRecords("ecmcPlcBinary.db","P=$(IOC):,PORT=MC_CPU1,ASYN_NAME=plcs.plc0.static.movesync,REC_NAME=-MoveSync,TSE=0,T_SMP_MS=100")

where IOC is defined at the top of the file:

epicsEnvSet("IOC" ,"$(IOC="LEBT-Iris:Ctrl-ECAT-01")")