The detailed documentation for the Greenbone Management Protocol (GMP) is now published in version 8.0 at the Greenbone TechDoc Portal:
GMP 8.0 is the API of the upcoming GOS 5 / GVM 10. The documentation allows to prepare for updating GMP-based scripts and applications in order to be compatible with GOS 5.
You should especially pay attention to the section “Compatibility Changes”.
There is a new section introduced with version 8.0: “Deprecation Warnings”. This section summarizes future API changes which the development team already decided. The commands still work in GMP 8.0 but it is recommended to use proposed alternatives already now to be prepared for a later migration to GMP 9.0 or beyond.