Non-negative parameter characterizing the dispersion of the quantity values that are being attributed to a measure based on the information used. 

Where possible, this should be derived from an experimental evaluation but can also be an estimate based on other information, e.g. experience.

One of seven UMM metadata profiles: Collection (UMM-C), Granule (UMM-G), Service (UMM-S), Variable (UMM-Var), Visualization (UMM-Vis), Tools (UMM-T), and Common (UMM-Common).

External person, institution or system that consumes user services provided by the payload data ground segment via data access or a science and service exploitation platform.

User support is a function inside the payload data ground segment to support external users to interact with the segment, to handle user registration, inquiries, complaints. This function is usually provided by a help desk.