Compared to print media, the advantage of electronic publications is faster availability of documents e.g. on the internet. Condition for publishing a document on the internet is the determination of the "electronic location" serving as publication address. At present, "electronic addresses" are commonly realised in the form of Uniform Resource Locators (URLs). Each URL is unequivocal worldwide. Therefore, URLs are used both for accessing the document and as identifier for referencing publications. URLs are either references within documents or links in information services, e.g. catalogues.
However, a change of the document's electronic location renders all references to the document unusable.
Authors and information providers should use permanent addressing mechanisms, such as Persistent Identifiers.