The purpose of the | Reference setdescriptor| is to describe the format of all other reference setsthat may be included in a release. A Descriptor held within the | Reference setDescriptor| describes the referencedComponentIdfield and the additional fields for the reference setsit describes. Each field is described using a conceptin the metadata. The type of each field is also described in the same way.

Patterns allow a number of different types of reference setto be defined, each of which will conform to the specified pattern, having the same release fileformat. The file format of each reference setpattern is described by a Descriptor Template. This Descriptor Template describes the format and number of additional fields held against members of reference setsconforming to the pattern, and provides an envelope within which those additional fields may be further refined for each reference setconforming to the pattern. The Descriptor Template for each pattern is provided in the section describing that pattern.

Each defined reference setthat conforms to a pattern will have its own Descriptor, that describes its own specific properties, and although reference setfield types must still conform to the Descriptor Template for the pattern, each field type may be further constrained using data sub-types specified in the metadata hierarchy. This provides some level of refinementto the constraintsthat may be applied to a reference setconforming to a particular pattern.

Patterns and Use Cases

The next table summarizes the use cases for reference sets(one per row) that are described in the following sections, and shows which reference setpatterns are used in each case:

Note: The letters shown after each pattern indicate the type and number of additional fields held against each member of a reference setconforming to that pattern, where 'C' is short for component, 'S' is short for String and 'I' is short for Integer .

Example: Reference setsconforming to the | Attribute valuetype| (C) pattern will have one additional field held against each member, a component reference; reference setsconforming to the |Simple type| pattern will have no additional fields held against each member.