PIN feature has been already discussed in this forum (use search).
"I have not worked with PINs on the 4K yet" - I do not believe you

Search also for "COS switchover":
Still, some general things about PIN in 4k:
Personal identification number (PIN)
The PIN is used for personal identification of a person to the system. Each station number can be assigned any number of PINs. The length of a particular PIN type is determined centrally. The PIN length may or may not be the same for the types of PINs described above. Each PIN (execpt COSXCD) must be unique throughout the system.
The same class of service changeover code (COSXCD) can be assigned to any number of stations. When a COSXCD that was previously assigned to a station is configured, the system outputs advisory message H38 to notify the user of this fact, and the command is still executed. If the user does not want the COSXCD to be assigned to multiple stations, he can delete the COSXCD for the station with DEL-PERSI:TYPE=PIN,PIN=number,STNO=number ;
In the case of PINC, it must also be determined at which position on the magnetic/chip card the PINC begins. (PIN pointer)
A 'Class of PIN' (COPIN) must be introduced for each type of PIN to be able to implement the PIN display feature and to be able to differentiate between the various types of PINs.
The COPIN defines the characteristics and functions of individual PIN applications such as the type of PIN (PINM, PINC, COSXCD, PCODE etc.), PIN length, PIN texts and various flags used to disable or enable specific functions.
The "class of PIN" (COPIN) is used for each PIN type in order to implement the PIN display feature and in order to distinguish between the different PIN types.
The characteristics of the COPINs (1 through 15) are summarized in the so-called COPIN table in which the following default values are assigned to the type of PIN:
Example:
- adding WABE code for activation/deactivation of PIN1
ADD-WABE:CD=*81,DAR=APIN1,CHECK=N;
ADD-WABE:#80,,,DPIN,N,,,,,,,,;
- adding PIN1 for station
ADD-PERSI:TYPE=STN,STNO=3402,PIN1="340200";
In PERSI:SYS -> length (number of digits) of PIN1 for example is given by: PIN1LEN parameter (6 digits 340200 in the above example )