Hypertext is a useful tool in managing complex documents and their inter-relationships. Documents are related by links which are attached to documents by hypermedia anchors. These links between anchors provide users with alternative reading routes and navigation strategies to retrieve information. In closed hypermedia systems anchors are usually contained in the document content, which prevents the documents from being used in applications that are unaware of the hypermedia structures and limits the documents formats to specialised hypermedia formats. One of the traits of open hypermedia systems is that the externalisation of anchor and link objects from the documents allows unrestricted use of different document formats and provides the opportunity to integrate third party applications as hypermedia viewers. This thesis examines open anchor methods that may be employed to maintain persistent references into documents. Extensions to the anchor definition provide more robust anchors, with greater utility than simple link place-holders. Anchors that reference objects within documents maintained by uncooperative applications are a requirement for integrating these applications as hypermedia viewers. This thesis introduces different methods of integration including a software proxy called the Universal Viewer. The Universal Viewer was produced to experiment with a general approach to providing all desktop applications with hypermedia facilities.