ISO 21127:2006 establishes guidelines for the exchange of information between cultural heritage institutions. In simple terms this can be defined as the curated knowledge of museums.

A more detailed definition can be articulated by defining both the intended scope, a broad and maximally inclusive definition of general principles, and the practical scope, which is defined by reference to a set of specific museum documentation standards and practices.

The intended scope of ISO 21127:2006 is defined as the exchange and integration of heterogeneous scientific documentation relating to museum collections. This definition requires further elaboration:

• The term "scientific documentation" is intended to convey the requirement that the depth and quality of descriptive information that can be handled by ISO 21127:2006 need be sufficient for serious academic research. This does not mean that information intended for presentation to members of the general public is excluded, but rather that ISO 21127:2006 is intended to provide the level of detail and precision expected and required by museum professionals and researchers in the field.
• The term "museum collections" is intended to cover all types of material collected and displayed by museums and related institutions, as defined by ICOM. This includes collections, sites, and monuments relating to fields such as social history, ethnography, archaeology, fine and applied arts, natural history, history of sciences and technology.
• The documentation of collections includes the detailed description of individual items within collections, groups of items and collections as a whole. ISO 21127:2006 is specifically intended to cover contextual information (i.e. the historical, geographical, and theoretical background that gives museum collections much of their cultural significance and value).
• The exchange of relevant information with libraries and archives, and harmonization with their models, falls within the intended scope of ISO 21127:2006.
• Information required solely for the administration and management of cultural institutions, such as information relating to personnel, accounting, and visitor statistics, falls outside the intended scope of ISO 21127:2006.

The practical scope of ISO 21127:2006 is the set of reference standards for museum documentation that have been used to guide and validate its development. ISO 21127:2006 covers the same domain of discourse as the union of these reference documents; this means that data correctly encoded according to any of these reference documents can be expressed in a compatible form, without any loss of meaning.