The issue of change of classification has been dealt with: E17 Type Assignment.
This issue should be called "how to model, when things undergo a change of nature".
In scope:
A new entity:Transformation, subclass of End of Existence and subclass of Begin of Existence, basically terminates one object and links it directly to its new nature. The thing itself splits into two distinct instances, only linked by the transformation event.
Alternatively, the notion of "input" and "output" of ABC Harmony could be adopted.
In Paris, October 2001, the change of nature of objects and how to model it was discussed:
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Things may grow or change slightlty. Detailed modelling of such processes is typically not of concern for cultural heritage documentation. Typically properties acquired over time are registered summarily (e.g. being a painter, even though not from the craddle).
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Things may change radically. This is of concern, in particular functional changes.
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Things may be consumed completely, the only continuity lies in part of the matter being preserved.
The crucial question is, when to start talking about a new object, and if, how to make clear the notion of continuity, i.e. preservation of important characteristics beyond the mere matter. Models dealing with real growth and slight changes are by far too copmplex for the purpose of integrated information access. Typical cases to model are:
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The object changes but preserves its nature and identity, e.g. replacement the hard disc of a computer. This is modelled as E11 Modification.
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The object ceases to exist, becaused it has been destroyed or consumed completely. E.g. a building used as quarry. This is modelled by the property "used object". The object itself ends to exist.
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The object preserves some recognizable identity. E.g. Tutankhamun becoming a mummy, a windmill becoming a house, a piece of money becoming a piece of jewelry.
The latter should be modelled by creating a new entity instance for the resulting object. The process of transformation implies a simultaneous destruction and production. This continuity should be modelled by:
E?? Transformation
subclass of: E64 End of Existence, E63 Begin of Existence
transformed (was transformed by): E77 Existence
resulted in (was result of): E77 Existence
Proposal accepted:
E?? Transformation
subclass of: E64 End of Existence, E63 Begin of Existence
transformed (was transformed by): E77 Existence
resulted in (was result of): E77 Existence
Monterey 22/2/2002.