A link is a hypermedia connection between two models. This hypermedia metaphor uses anchor markers and links to mark the source and destination places within one model or between two different models. The models can be in separate documents.

Link creation

To create a link between two anchor markers, you must specify the anchor markers. The situation is similar to copying and pasting data (where you need to specify a source and destination).

Link deletion

When you delete a link, you do not delete the anchor markers at either end of the link.

A bidirectional link has two elements: a link that has anchor marker A as its source anchor marker and anchor marker B as its destination anchor marker (and is owned by anchor marker A); and another link that has anchor marker B as its source anchor marker and anchor marker A as its destination anchor marker (and is owned by anchor marker B).

Each separate unidirectional link is marked to indicate that it is part of a bi-directional pair. If you remove such a link from one document, you need to remove the corresponding link in the other direction.

Operations on links

Links can be traversed. Traversing a link activates a logical context switch for a user (or an object) interacting with a document. The standard commands TPushDataCommand and TPullDataCommand can move data across a link from one anchor marker to another.

Commands on links

Links are connections between two anchor markers and are always owned by the anchor markers. The standard commands on links are:

Types of links

Only one type of link is provided by the Compound Document framework. This link identifies the source and destination anchor markers for the link, and might contain attributes for the link.

Directionality of links

Links are unidirectional in the Compound Document framework. Bidirectional links are simulated by using two unidirectional links.

Errors on links

Link referential integrity is not guaranteed. Anytime a link is followed, make sure the client is prepared to handle a link where the destination is no longer valid.

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