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1.9.1 Versioning and hypertext
At this point in time, the assumption that the artifacts in artifact-based collaboration are
hypertext or hypermedia objects is unexceptional. Even if hypertext links are not parts of
the objects themselves (an increasingly unlikely state of affairs), it is a near certainty that
hypertext links into the artifacts we share are becoming more and more common and impor-
tant.
The topic of version maintenance has been a traditional part of hypertext system design
since the field’s inception (Engelbart 1963; Nelson 1987). In the traditional view, versioning
is presented as a desirable or essential convenience for a hypertext author (Haake 1991a;
Haake 1991b). Indeed it is this justification for version control that Halasz questioned in
(Halasz 1988). However, some of the most important arguments for the importance of ver-
sion control and history retention are not solely for user version control capabilities, but to
ensure correctness and consistency in the distributed editing of collaborative, constructive
hypertexts (Joyce1988).
The experimental system RHYTHM (Maioli, Sola et al. 1994; Maioli, Sola et al. 1994)ex-
plored the use of versioning specifically to support accountability and fine-grained tracking
of hypertext anchors across revisions of text nodes in hypertext documents. RHYTHM also
implemented transclusion—structural data sharing between documents, using the same
mechanisms that it used for version maintenance.
Version management has some important virtues to offer any system that includes hyper-
text linking, since immutable versions can preserve the state of a shared object at the time
of link creation. This is useful because the meaning of a link is determined partly by the
contents of its endpoints. Even subtle changes in a linked document may radically change its
meaning in the context of an editorial link asserting bias or inaccuracy. In a collaborative
context, the attachment of annotations may form a significant channel of communication
between the authors, and the ability to view annotations in conjunction with their original
1.9.1 Versioning and hypertext
At this point in time, the assumption that the artifacts in artifact-based collaboration are
hypertext or hypermedia objects is unexceptional. Even if hypertext links are not parts of
the objects themselves (an increasingly unlikely state of affairs), it is a near certainty that
hypertext links into the artifacts we share are becoming more and more common and impor-
tant.
The topic of version maintenance has been a traditional part of hypertext system design
since the field’s inception (Engelbart 1963; Nelson 1987). In the traditional view, versioning
is presented as a desirable or essential convenience for a hypertext author (Haake 1991a;
Haake 1991b). Indeed it is this justification for version control that Halasz questioned in
(Halasz 1988). However, some of the most important arguments for the importance of ver-
sion control and history retention are not solely for user version control capabilities, but to
ensure correctness and consistency in the distributed editing of collaborative, constructive
hypertexts (Joyce1988).
The experimental system RHYTHM (Maioli, Sola et al. 1994; Maioli, Sola et al. 1994)ex-
plored the use of versioning specifically to support accountability and fine-grained tracking
of hypertext anchors across revisions of text nodes in hypertext documents. RHYTHM also
implemented transclusion—structural data sharing between documents, using the same
mechanisms that it used for version maintenance.
Version management has some important virtues to offer any system that includes hyper-
text linking, since immutable versions can preserve the state of a shared object at the time
of link creation. This is useful because the meaning of a link is determined partly by the
contents of its endpoints. Even subtle changes in a linked document may radically change its
meaning in the context of an editorial link asserting bias or inaccuracy. In a collaborative
context, the attachment of annotations may form a significant channel of communication
between the authors, and the ability to view annotations in conjunction with their original
