What do the first three letters of the I-797 notice receipt indicate?

Below we have included information defining what the 3-letter USCIS codes mean:

• CSC – California Service Center
• EAC – Eastern Adjudication Center (now known as Vermont Service Center)
• IOE – ELIS (efile)
• LIN – Lincoln Service Center (now known as Nebraska Service Center)
• MSC – Missouri Service Center (now known as National Benefits Center)
• NBC – National Benefits Center
• NSC – Nebraska Service Center
• SRC – Southern Regional Center (now known as Texas Service Center)
• TSC – Texas Service Center
• VSC – Vermont Service Center
• WAC – Western Adjudication Center (now known as California Service Center)