MM : Maintain header text PR/PO

I know this from one of my MM module's colleague.

Maintain Header Text PR :
SPRO -> Real Estate -> Tools -> Central Correspondence Maintenance -> Text ID s
To maintain :
PR (me51n/me52n/me53n) text id
- PR Header Text, object name : EBANH, with ID start from B01 - B99
- PR Item Text, object name : EBAN, with ID start from B01 - B99
PO (me21n/me22n/me23n) text id
- PO Header Text, object name : EKKO, with ID start from F01 - F99
- PO Header Text, object name : EKPO, with ID start from F01 - F99

That table also keeps the maintenance Text IDs for other SAP Standard tcode, but i dont have the documentation furthermore.

If you have any documentation about this, feel free to share :)