XLinks are a key component in the PageSeeder architecture. Sometimes their role is obvious (cross-references), and sometimes it is less obvious (a new document).
They are a key tool for developers, allowing document fragments to be stored and edited separately but assembled for publishing. This mechanism is useful for implementing typical publishing capabilities such as indexes, footnotes, endnotes, chapters etc.
XLinks are expressed in a syntax that is both rich and customizable. This makes it possible to give links different contexts for processing and makes it possible to keep the structure of document fragments simpler than would be required with a less rich link syntax.