Every observer at every location at every time has a different perspective. Perspectives are infinite and incalculable. They are the superset from which practical Diversity in Social Systems is drawn.
See Perspective (Pattern) and Time Travel Project.
Arrows diagram ⇒ Graphviz DOT layout
[…] the final and crucial addition to this meta-ontology — are the spaces in which these URIs are stored, associated and contextualised. Perspectives are really just graphs in which the nodes are Expression references (i.e. Expression URIs). Basic Perspectives are always local, private and fully controlled by Agent/user. post 
Expressions are basically data objects that were spoken into being by an Agent, using a chosen Language.