OM_Observation used as property values

There are a couple of things that needs to be set in the way we encode OM_Observation, specially when we use them as property values.

There are two cases when we use OM_Observation as values

1. When using relatedObservation on any sub types of SF_SamplingFeature
2. Using a specific property (such as GW_FluidBody/gwBodyVolume)

OM_Observation has a mandatory featureOfInterest that is supposed to point back to the feature that is the “bearer of the property”. In case 2) , the bearer of the property is obviously the feature having this property, so technically, we should constrain featureOfInterest to link back to that feature

Eg: we should technically have this

Issues: (Question in red)

Cases where the bearer of property is not a feature

(GW_WaterBudget for instance, is a Type, not a Feature), so we can’t use featureOfInterest to link it back

In this case, we should point back to the refers to this Type ? In case of WaterBudget, who does ?

Same Observation shared by multiple properties

nothing prevents more than one property to point to the same Observation (by reference), which becomes a problem for the featureOfInterest (foi is 1..1). It can be done schematically even if does not make sense logically. Should we have a clause that says “OM_Observation that are values of explicit properties will use featureOfInterest to identify the legitimate bearer of properties. Reference to OM_Observation from an explicit property when the property bearer is not the owner is invalid” (should it be invalid ?, or can it have another meaning)

ObservedProperty

OM_Observation also has an observedProperty. Technically, this should be a reference to the property (the property type, not a specific instance of the property) this observation is about. We have several options (which one should we use)

1. Use a reference to schemas - like this "http://ngwd-bdnes.cits.nrcan.gc.ca/service/gwml/schemas/2.1/gwml2-well.xsd#GW_WellType.gwWellConstructedDepth (there are no good way to link to a property, it has no identity - (apparently, new ISO 19109 will change this)
2. Use a good old vocabulary unrelated to domain schema - with the benefit of having more precise definition of the phenomena than the schema provide

-- EricBoisvert - 07 Jul 2015