Calling procedure from included .mod file, without explicit `use` statement

[ivanpribec]

Take a look at this answer:

What does implicit none (type,external) do?

For reference, I’ll answer the subject question. implicit none (type,external) is a Fortran 2018 feature. implicit none(type) is the same as implicit none, disabling all implicit typing. implicit none(external) requires that any procedures referenced either have an explicit interface or be declared EXTERNAL. You can combine the options. Compilers supporting this may have a command line option to imply implicit none (external) in the same manner as options to disable implicit typing.

I’m guessing your module could have just picked up the procedure from the library and used it as an (implicit) external procedure. It does seem a bit weird though, as module procedures have their names mangled.