This document was initiated to improve the capability to manage external services that affect UAS operations, as a means to support safety in the Specific Category. Considering that the GNSS receiver is the primary navigation sensor for most UAS, the level of performance of GNSS services, and especially multi-GNSS, has a direct relation with flight safety for UAS, both in nominal and non-nominal conditions according to the particular operational context where it is used. The term “multi-GNSS” is used since there are several GNSS constellations that could be used to provide positioning information to UAS. This document details some specific constellations/systems/signals due to legacy reasons, global coverage and general public accessibility. The resulting standards will support UAS operators in achieving approval for specific operations in regards to the inherent safety risks associated to the use GNSS services in UAS operations.