canonical | commentary | quotation | reference | external |
The notion of link directionality was first mentioned in Section 3.4. Recall that the physical direction of a link defines the manner in which readers are expected (by the link's author) to follow the link. Readers of a link directed from A to B, for example, are expected to proceed to B after having read A.
There is another kind of link direction dictated by the link's type. We call this the semantic direction of the link. For example, a Refutation link connecting A and B can be read "A refutes B" and thus the semantic direction is from A to B. However, the physical direction can differ. The refuting author may wish readers to see refutation A only after having read the refuted node B.
In fact, it is generally the case that for commentary links, the physical direction is opposite to the semantic direction. Consider, for example, a comment link of the form "C comments on N." Semantically, the link points from C to N, while the physical direction usually goes the other way. This is because it is rare (though possible) to read the commentary C before reading its object N. (Trigg, n.p.)
Adrian Miles: Hypertext syntagmas: cinematic narration with links
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