OCNSP tries to be for corporate/private networks what OWASP is for Web Application.
Other projects are similar and better, but none of them is comprehensive: https://www.owasp.org/index.php/Penetration_testing_methodologies
Find the standard here : https://github.com/astar-security/OCNSP/wiki
For any question/support about this project, please visit: www.astar.org.