[gdal-dev] GFS with condition on the second last element

[Raymond Nijssen]

Hi list,

I'm trying to read a complex gml file that includes values that need to 
be selected on an xml attribute. This is possible to do with a condition 
in the gfs file, but the example only covers having the attribute on the 
last element in the elementPath:

https://gdal.org/drivers/vector/gml.html#using-conditions-on-xml-attributes


But mine is on the 2nd last element, like this:

```
         <imaer:result>
             <imaer:Result resultType="DEPOSITION" substance="NH3">
                 <imaer:value>0.01909</imaer:value>
             </imaer:Result>
         </imaer:result>
         <imaer:result>
             <imaer:Result resultType="DEPOSITION" substance="NOX">
                 <imaer:value>0.001341</imaer:value>
             </imaer:Result>
         </imaer:result>
```

So I'd like to do something like this in my gfs:

```
     <PropertyDefn>
       <Name>nh3</Name>
       <ElementPath>result|Result|value</ElementPath>
       <Condition>result|Result at substance='NH3'</Condition>
       <Type>Real</Type>
     </PropertyDefn>
```

to only catch the value where substance = NH3. I've been trying many 
options but no success yet.


Is this even possible? And if so, how?

Thanks!
Raymond