Thanks in advance! -- David Coyle, USGS, OWI SE, NWISWeb
The problem is that we want to be able to provide three "items":
1) The actual value of the code -- ie. "S"
2) The domain it refers to -- ie. geLevMethCd, or gwLevStatusCd,
3) The definition of that code within the domain -- xlink:href="http://waterdata.usgs.gov/nwisweb/rdf?gwLevStatusCd=S"
So the first approach is to use the basic approach as follows (based on one of the well-known examples from the docs):
However, if we can't find a valid way to include the raw code value we may just have to either overload title like -->> xlink:title="gwLevStatusCd:S" or make the user parse it off the end of the URI.
So this discussion brought forward the question should we use the swe:Category. The counter argument of course is that this approach is not complex and not warranted. An advantage of this approach (to me at least) is that we have use of the optional swe:label, as well as the optional swe:codespace. So here is the counter-proposal that we are currently considering:
The counter example proposed earlier and now introduces the use of swe:label which addresses the concern about showing the domain it refers to, as well as a place to show the value (swe:value). It also makes it possible to eliminate the xlink "title" field - which may be unclear in its meaning for users. The swe:codespace field can be removed for now but is available for possible future use:
Re: How to best represent Qualifier Codes in WaterML2 timeseries
the XLink approach with the xlink:href, xlink:title and xlink:label
attributes is certainly a compact variant to provide the information
but in this case you have to define how the user has to interpret the
attributes, for example by a profile definition.
With the swe:Category approach increases the doc but I guess it is
easier to interpret and directly understandable. This approach is also
used in the OGC WaterML 2.0 Qualifier example . And as you mentioned,
the optional elements/attributes of the swe:Category can be used in the
future to add more information.