Issue 263: Merging Classes

In 31st joined meeting of the CIDOC CRM SIG, ISO/TC46/SC4/WG9 and the 24th FRBR - CIDOC CRM, resolving the issue 234, the crm-sig  proposed to add a new issue about if the classes E92 Spacetime Volume and E93 Spacetime Snapshot should be merged.

E92 Spacetime Volume

Subclass of: E1 CRM Entity

Scope note:  This class comprises 4 dimensional point sets (volumes) in physical spacetime regardless its true geometric form. They may derive their identity from being the extent of a material phenomenon or from being the interpretation of an expression defining an extent in spacetime. Intersections of instances of E92 Spacetime Volume, Place and Timespan are also regarded as instances of E92 Spacetime Volume.  An instance of E92 Spacetime Volume is either contiguous or composed of a finite number of contiguous subsets. Its boundaries may be fuzzy due to the properties of the phenomena it derives from or due to the limited precision up to which defining expression can be identified with a real extent in spacetime. The duration of existence of an instance of a spacetime volume is trivially its projection on time.

Examples:

• the spacetime Volume of the Event of Ceasars murder
• the spacetime Volume where and when the carbon 14 dating of the "Schoeninger Speer II" in 1996 took place
• the spatio-temporal trajectory of the H.M.S. Victory from its building to its actual location
• the spacetime volume defined by a polygon approximating the Danube river flood in Austria between 6^th and 9^th of August 2002

Properties:

P160 has temporal projection: E52 Time-Span
P161 has spatial projection: E53 Place

E93 Spacetime Snapshot

Subclass of: E92 Spacetime Volume

Scope note: This class comprises instances of E92 Spacetime Volume that result from intersection of instances of E92 Spacetime Volume with an instance of E52 Time-Span.  The identity of an instance of this class is determined by the identities of the  constituing spacetime volume and the time-span.

This class can be used to define temporal snapshots at a particular time-span, such as the extent of the Roman Empire at 33 B.C., or the extent occupied by a museum object at rest in an exhibit. In particular, it can be used to define the spatial projection of a spacetime volume during a particular time-span,  such as the maximal spatial extent of a flood at some particular hour, or all areas covered by the Poland within the 20th century AD

Properties:

P162 is restricted by: E92 Spacetime Volume
P164 is restricted by: E52 Time Span

Heraklion, Crete , September 2014