What is a savepointLevel ?

Hello hackers,

What exactly is a savepointLevel?

They seem to have been there for 15 years[1], diligently copied from
parent transactions to children, fastidiously checked to avoid crossing
a level on rollback or release, but does anything ever change the level
from its initial value? I'm drawing a blank[2].

Regards,
-Chap


[1]

https://git.postgresql.org/gitweb/?p=postgresql.git;a=blame;f=src/backend/access/transam/xact.c;h=fd5d6b5;hb=90cb9c3#l93

[2]
https://git.postgresql.org/gitweb/?p=postgresql.git&a=search&h=0516c61b&st=grep&s=savepointLevel