Admissions XX or Admission XX?

Dear professional English teachers,

I always wonder which of the forms is actually correct in an example like this:
1. Please read the admissions procedure.
2. Please read the admission procedure. (In this case, "admission" is used as an adjective, so it should not be "admissions" I guess.)

Is #1 correct grammatically? I just do not understand why it will be "admissions procedure," which seems to be the form of "noun + noun."

Someone, please help me understand it.

Admissions is plural in that context. Click Office of Public Relations: University Style Guide and Writing Style Standards A to Z

All the best. :-D

Thank you for your references.
They were helpful.

Well, I cannot come up with other examples of the form "plural noun + noun,"
so I will not be able to ask you further questions on this matter at the moment. However, is it common and grammatically correct to make the form "plural noun + noun" instead of making it to "adjective + noun"?