LAS 6.1: configuring categories

[Cyndy Chandler <cchandler@xxxxxxxx>]

Good day ...

I'm trying to set up categories for several datasets, each of which has
hundreds of variables of in-situ profile data.  I have been able to set
up categories to organize the datasets into logical groups, see
http://usjgofs.whoi.edu/las/servlets/dataset

now I would like to further categorize the datasets in the 'In-situ Data
Synthesis' category into thematic groups (ie. Chemistry, Biology, etc.).

So my LAS hierarchy would be:
In-situ Data Synthesis
  U.S. JGOFS Arabian Sea TM Bottle Data
     Chemistry
        Ammonium
        Nitrate, analysis for low level concentrations
        particulate organic Nitrogen
        etc.
     Biology
        little bugs
        cute bugs
        etc.
     etc. ... rest of disciplines
  etc. ... rest of in-situ datasets
etc. ... rest of dataset categories


I tried doing this for the dataset named 'U.S. JGOFS Arabian Sea TM
Bottle Data' but I don't have the syntax correct.  I was trying to model
the examples presented in
http://ferret.pmel.noaa.gov/Ferret/LAS/Documentation/manual/customize.html#Categories

my dataset.xml file includes these lines:
  <variables>
   <NH4 units="micromoles N/liter" name="Ammonium">
    <link match="/lasdata/grids/JGOFS_bottleTM_arabian_grid"/>
   </NH4>
   <NO3_nano units="nanomoles/liter" name="Nitrate, analysis for low
level concentrations">
    <link match="/lasdata/grids/JGOFS_bottleTM_arabian_grid"/>
   </NO3_nano>
   <PON units="micromoles/liter" name="particulate organic Nitrogen">
    <link match="/lasdata/grids/JGOFS_bottleTM_arabian_grid"/>
   </PON>

so I tried to make a catalog.xml file to put all those variables in the
category 'Chemistry'
    <category name="In-situ Data Synthesis">
	<category name="U.S. JGOFS Arabian Sea TM Bottle Data">
	    <filter action="apply-dataset" equals="U.S. JGOFS Arabian Sea TM
Bottle Data"/>
              <category name="Chemistry">
                <filter action="apply-variable" equals="Ammonium">
                <filter action="apply-variable" equals="Nitrate,
analysis for low level concentrations">
                <filter action="apply-variable" equals="particulate
organic Nitrogen"/>
                </filter>
	      </category>

        </category>

I also tried rearranging the lines like this:
     <category name="U.S. JGOFS Arabian Sea TM Bottle Data">	    
         <category name="Chemistry">
	     <filter action="apply-dataset" equals="U.S. JGOFS Arabian Sea TM
Bottle Data">
             <filter action="apply-variable" equals="Ammonium">
             <filter action="apply-variable" equals="Nitrate, analysis
for low level concentrations">
             <filter action="apply-variable" equals="particulate organic
Nitrogen"/>
             </filter>
	 </category>

     </category>

but when I try to regen my server LAS returns this error:
Using catalog file 'catalog_smp.xml' ...
mismatched tag at line 28, column 9, byte 1256:
                <filter action="apply-variable" equals="Nitrate,
analysis for low level concentrations"/>
                </filter>
              </category>
========^
        </category>

this approach (because I really do want boolean OR at the variable
level)
        <category name="U.S. JGOFS Arabian Sea TM Bottle Data">	    
            <category name="Chemistry">
	        <filter action="apply-dataset" equals="U.S. JGOFS Arabian Sea
TM Bottle Data">
                 <filter action="apply-variable" equals="Ammonium"/>
	         </filter>
                 <filter action="apply-variable" equals="Nitrate,
analysis for low level concentrations"/>
		</filter>
	    </category>
        </category>
yields:
mismatched tag at line 28, column 4, byte 1246:
                 </filter>
                 <filter action="apply-variable" equals="Nitrate,
analysis for low level concentrations"/>
                </filter>
===^
            </category>
        </category>

and various other interpretations, but you get the idea ...

Has anyone tried using categories in a similar fashion?  
Any suggestions?

Thanks much,
Cyndy Chandler

PS - are the filter action attributes apply-dataset and apply-variable?
or apply-datasets and apply-variables? or either? both are used in the
examples.