When recently looking at the libgomp documentation, here the current GCC 13 version,
   https://gcc.gnu.org/onlinedocs/gcc-13.1.0/libgomp/Runtime-Library-Routines.html
I found both the order confusing and the wording:
"The routines are structured in following three parts:"

as I did not see any separation. In the "info" version, one could indeed see:

   Control threads, processors and the parallel environment.  They have C
   linkage, and do not throw exceptions.
      (long list of routines)
   Initialize, set, test, unset and destroy simple and nested locks.
     (short list)
   Portable, thread-based, wall clock timer.
      (two rourines)
   Support for event objects.
      (one routine)

which are the three parts - or do I count four?

OpenMP itself split the long list into several parts; the attached commit does
likewise. Result (before or after the change, depending when you have a look):
   https://gcc.gnu.org/onlinedocs/libgomp/

(The commit also fixed a typo in the OMP_ALLOCATOR example.)

Committed as r14-2681-g506f068e7d01ad

* * *

If you look at the '@c' items in the '@menu' you will also see which routines
are missing - either
* because they have not yet been documented - or
* because they have not yet been implemented.

37 routines fall into the first category. Possibly, some of the dicumented routines
need to be updated as well, if somethines has changed after their initial
implementation (or to improve the wording).

See also https://gcc.gnu.org/PR110364 for improvements which should eventually be done.

Tobias

PS: If someone feels bored, proof reading or adding a description for the missing routines
would be useful :-)  - But assume/fear that no one feels bored :-)
-----------------
Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634 München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB 106955