Determining Oracle Database Edition

The other day I debugged some Oracle provided utilities and came across another way of determining an Oracle Database edition. It does not require a running database instance.

The Oracle code was checking what is inside the $ORACLE_HOME/lib/libedtn19.a library:

# Enterprise Edition
[oracle@rac1 lib]$ ar t /u01/app/oracle/product/19.3.0/dbhome_1/lib/libedtn19.a
vsnfent.o

# Standard Edition
[oracle@rac1 lib]$ ar t /u01/app/oracle/product/19.3.0/dbhome_2/lib/libedtn19.a
vsnfstd.o

As it can be seen, it is vsnfstd.o for Standard vs vsnfent.o for Enterprise.
It appears to be a file for each edition and the file libedtn19.a contains the edition of that specific Oracle Home:

[oracle@rac1 lib]$ find . -name 'libedtn19*a' -print -exec ar t '{}' \;
./libedtn19_xp.a
vsnfxp.o
./libedtn19_ent.a
vsnfent.o
./libedtn19_cse.a
vsnfcse.o
./libedtn19_cee.a
vsnfcee.o
./libedtn19.a
vsnfent.o
./libedtn19_hp.a
vsnfhp.o
./libedtn19_std.a
vsnfstd.o

It has no effect on V$VERSION output whatsoever, and it obviously cannot be used to change one edition to another.
Yet I discovered that srvctl checks that libedtn19.a file in certain scenarios to determine whether or not some edition specific features should be allowed.
Per my research, that library was introduced in Oracle 18c.