Of course there is an ICAO Training Manual, Doc 7192 - B5 for PPL training.
From ICAO Annex 1
1.2.8 Approved training
Note.— The qualifications required for the issue of
personnel licences can be more readily and speedily acquired
by applicants who undergo closely supervised, systematic and
continuous courses of training, conforming to a planned
syllabus or curriculum. Provision has accordingly been made
for some reduction in the experience requirements for the
issue of certain licences and ratings prescribed in these
Standards and Recommended Practices, in respect of an
applicant who has satisfactorily completed a course of
approved training.
Approved training shall provide a level of competency at least
equal to that provided by the minimum experience requirements
for personnel not receiving such approved training.