Indirect key-based addressing

The concepts described below are critical for a full understanding of keys and key processing.

Key scopes enable map authors to specify different sets of key definitions for different map branches.

For topic references, image references, and other link relationships, resources can be indirectly addressed by using the @keyref attribute. For content reference relationships, resources can be indirectly addressed by using the @conkeyref attribute.

When referencing key definitions that are defined in a different key scope, key names might need to be qualified with key scope names.

A map can use scoped keys to reference keys that are defined in a different root map. This cross-deliverable addressing can support the production of deliverables that contain working links to other deliverables.

Key references can resolve as links, as text, or as both. Within a map, they also can be used to create or supplement information on a topic reference. This topic covers information that is common to all key processing, regardless of how the key is used.

Keys can be used to create or redirect links and cross references. Keys also can be used to address resources such as images or videos. This topic explains how to evaluate key references on links and cross references to determine a link target.

While <topicref> elements are used to define keys, they also can reference keys that are defined elsewhere. This topic explains how to evaluate key references on <topicref> elements and its specializations.

Key references can be used to pull text from the key definition. This topic explains how to generate text from a key definition, regardless of whether the key reference also results in a link.

This section of the specification contains examples and scenarios. They illustrate a wide variety of ways that keys can be used.