Grab all sub categories from 1 category (4 levels deep)
<mvt:item name="toolkit" param="subcat|ccount|g.Category_Code" />
<mvt:if expr="ccount GT 0">
<mvt:foreach iterator="sub_category" array="sub_categories">
&mvt:sub_category:code;,
<mvt:item name="toolkit" param="subcat2|ccount2|l.all_settings:sub_category:code" />
<mvt:if expr="ccount2 GT 0">
<mvt:foreach iterator="sub_category2" array="sub_categories2">
&mvt:sub_category2:code;,
<mvt:item name="toolkit" param="subcat3|ccount3|l.all_settings:sub_category2:code" />
<mvt:if expr="ccount3 GT 0">
<mvt:foreach iterator="sub_category3" array="sub_categories3">
&mvt:sub_category3:code;,
<mvt:item name="toolkit" param="subcat4|ccount4|l.all_settings:sub_category3:code" />
<mvt:if expr="ccount4 GT 0">
<mvt:foreach iterator="sub_category4" array="sub_categories4">
&mvt:sub_category4:code;,
</mvt:foreach>
</mvt:if>
</mvt:foreach>
</mvt:if>
</mvt:foreach>
</mvt:if>
</mvt:foreach>
</mvt:if>