[obs] Joining DwC, OBOE, PO and PATO

[Cam Webb]

Hi Matt,

>> Or even to the dwc:Occurrence itself if we can consider an observation 
>> to be a type of Occurrence.
>
> Fascinating.  In high-level conceptual terms, I have always considered an
> occurrence to be a form of observation, not the other way around.  This is
> because an occurrence records the presence or absence of an individual of a
> species at a particular place and time.  An observation is a record of any
> type of measurement within any context, and so might include, for example,
> the measurement of the size of an organism at a location and time.  This
> observation can then be used to infer that the organism was present at that
> place and time, and therefore that we can say it occurred there as well.

The participants in the current discussion on tdwg-content seem to be in 
agreement that that an observation (which may or may not eventually have 
its own token node) is a form of occurrence.  Other forms of occurrence 
include specimens and images.  Not all (recorded) occurrences would count 
as observations.  But the base (implicit and explicit) semantic models of 
DwC and OBOE are different, and I don't think there is any fundamental 
concept conflict here.

Best,

Cam