Issue 107: P33 subproperty of P12

P33 used specific technique (was used by) should be subproperty of
P12 occurred in the presence of (was present at)

(Scope note: This property describes the active or passive presence of a persistent item in an event without implying any specific role.
It connects the history of a thing with the place and date of an event. For example, an object may be the desk, now in a museum on which a treaty was signed. The presence of an immaterial thing implies the presence of at least one of its carriers. Examples: Deckchair 42 (E19) was present at The sinking of the Titanic (E5))

Reason: the specific technique participates through its carrier, as any immaterial object can do.

30/9/2002