What is SRN IN SAP : How to create Service Entry In SAP : ML81N

What is SRN IN SAP : ML81N : How to use SRN IN SAP :-
What is SRN In SAP : -
Service Received Note (SRN) is a document issued by the buyer upon delivery of goods or services. It is to check or validate the delivered goods by the seller for the verification and record purpose.
Based on the order placed by the buyer, seller provides the goods or services. Procurement Team raises SRN code once the services reach the facility.
It is the responsibility of the store person to ensure that the received services are properly checked and entries are made accordingly.
Then the SRN Goes for the approval.
SRN T-Codes :-
ML81N