what is this line ref # ?

Hello, please tell me, what is this line ref # ?, in the photo I pointed out, it is attached where you can change the name of this line ref # , thank you?

Hi,
You can modify the Ref field of Property modification page in 2 files:
root > administrator > components > com_osproperty > classes > property.html.php
and
root > components > com_osproperty > helpers > layouts > propertyedit.php
Thanks
Dam