Need to know why in Manage Schedule page ECD dates and TA status are updating in time and labor Modu

We are using Peopletools 8.54 version. 9.2 application, PUM 12.

The below code is the delivered code in the following object-->SCH_MNG_PERIOD.DERIVED_SCHED.SAVE_PB.FieldChange

If the Employee is picked by the Time Admin process, then TA status in the PS_TL_TR_STATUS will be 'X'. Now if Scheduling Manager is changing the shift in the MSS--> Time reporting--> Manage Schedule--> Manage Schedule page for any future date , then ECD date and TA status are getting updated to scheduled date and TA status to Y as per the below code. Could you please let us know the below highlighted code should be