  The availability of interaction devices has raised interest in techniques to
support the user interface (UI). A UI specification describes the functions
that a system provides to its users by capturing the interface details and
includes possible actions through interaction elements. UI developers of
interactive systems have to address multiple sources of heterogeneity,
including end users heterogeneity and variability of the context of use. This
paper contributes to the notion of interactivity and interfacing by proposing a
methodology for producing engineering-type diagrams of (abstract) machine
processes that can specify uniform structure and behavior of systems through a
synchronic order of states (stages): creation, release, transfer, receive, and
process. As an example, the diagrammatic methodology is applied to
conceptualizing space as a machine. The resulting depiction seems suitable for
use in designing UIs in certain environments.
