The multi-level category filter is a new enhancement in Notes Domino R852. It's an addition to the categoryFilter feature in the View data source that allows you to filter a view by the category and then the sub-category. It's a neat way for refining your view document collection even further than just by the main category.

For example, setting categoryFilter="Fruit" will display all documents under the 'Fruit' category, while categoryFilter="FruitApples" displays the documents under the 'Fruit' category and the 'Apples' subcategory.

For a slightly more advanced example, take the XPages Demo App from OpenNTF - and hitting the category filtering example - http://yourDominoServer/xpages.nsf/viewFilteringCategory.xsp 

This sample xpage has a viewPanel that displays a Notes view which has categories as well as subcategories. There is also a combo box which drives the categoryFilter - when a selection is made a refresh happens to the view panel and it then displays only the documents of that category. 

...             <xp:comboBox id="comboBoxViewFilterText1"
                    value="#{viewScope.filterCat01}">
                    <xp:selectItem itemLabel="No Filtering" itemValue="">
                    </xp:selectItem>
                    <xp:selectItems>
                        <xp:this.value><![CDATA[#{javascript:@Unique(@DbColumn(@DbName(),"xspFiltersView",1))}]]></xp:this.value>
                    </xp:selectItems>
                    <xp:eventHandler event="onchange" submit="true"
                        refreshMode="partial" refreshId="viewPanel4CategorizedView">
                    </xp:eventHandler>
                   
                </xp:comboBox>
                <xp:br></xp:br>
                <xp:viewPanel rows="30" id="viewPanel4CategorizedView">
...
                    <xp:this.data>
                        <xp:dominoView var="xspFiltersViewCategory"
                            viewName="xspFiltersViewCategory"
                            categoryFilter="#{javascript:viewScope.filterCat01}">
                        </xp:dominoView> ...

...             <xp:comboBox id="comboBoxViewFilterText1"
                    value="#{viewScope.filterCat01}">
                    <xp:selectItem itemLabel="No Filtering" itemValue="">
                    </xp:selectItem>
                    <xp:selectItems>
                        <xp:this.value><![CDATA[#{javascript:@Unique(@DbColumn(@DbName(),"xspFiltersView",1))}]]></xp:this.value>
                    </xp:selectItems>
                    <xp:eventHandler event="onchange" submit="true"
                        refreshMode="partial" refreshId="viewPanel4CategorizedView">
                    </xp:eventHandler>
                    <xp:selectItem
                        itemLabel="***Multilevel Categories*** "> </xp:selectItem>

                    <xp:selectItems>
                        <xp:this.value><![CDATA[#{javascript:@Unique(@DbColumn(@DbName(),"xspFiltersView",1)
+"\"+
@DbColumn(@DbName(),"xspFiltersView",2))}]]></xp:this.value>
                    </xp:selectItems>
                </xp:comboBox>
...

One limitation you might experience with this enhancement is when the sorting of the subcategory column is determined partly by a preceding column in the categorized Notes view. Here the subcategory filtering will work up to a certain point (where the subcategory sorting is changed by a preceding column sorting) in XPages. For this issue (PHAN87ALDT) we're seeking to address in the next release of Notes Domino.

Hope this helps.

p.

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