The Question of Arcs

Moving Toward Complete Extended Link Processing

From Sets to Graphs After considerable debate on the xlxp-dev mailing list and internally at the W3C, the XLink Working Group added Arcs to extended links. Arcs (represented by xlink:type="arc") allow developers to describe paths between the resources identified by locators within an extended link.
XArc One proposal would have replaced the entire framework of XLink with a simple origin-destination scheme. The distinction between simple and extended links would have vaporized, and links could be in-line or out-of-line as appropriate.
Compromise The XLink Working Group's proposal allows the use of arcs inside of extended links, and connects them to label values on locators and resources. If wildcarding isn't used, so specification of traversal paths is n² where n is the number of labels. (This is much better than previous versions, which used ID values for each locator.) Missing values for from and to are considered to represent 'all'.