This is an example of a MODO config file that sets up a properties form that is only visible for an item that contains a given package. One more snatch from James O'Hare.

ItemPackageFormFilter.CFG

    <atom type="Filters">
        <hash type="Preset"     key="ffr_morphCage.package:filterPreset">
            <atom type="Name">Morph Cage View</atom>
            <atom type="Enable">1</atom>
            <list type="Node">1 .group 0 &quot;&quot;</list>
            <list type="Node">1 packagename ffr_morphCage</list>
            <list type="Node">-1 .endgroup </list>
        </hash>
    </atom>

    <atom type="Attributes">
        <hash type="Sheet" key="ffr_morphCage.package:sheet">
            <atom type="Label">Cage View Settings</atom>
            <atom type="Filter">ffr_morphCage.package:filterPreset</atom>
            <atom type="Group">itemprops/render</atom>

            <hash type="InCategory" key="itemprops:general#head">
                <atom type="Ordinal">129</atom>
            </hash>

            <list type="Control" val="ref 11451745884454:sheet"></list>
            <list type="Control" val="ref 803465746857872:sheet"></list>

            <list type="Control" val="div ">
                <atom type="Label">Cage View</atom>
                <atom type="Hash">03912389563401:control</atom>
                <atom type="Alignment">full</atom>
            </list>

            <list type="Control" val="cmd item.channel morphBaseDraw ?">
                <atom type="Label">Draw Base Mesh</atom>
            </list>
            <!-- etc -->
        </hash>
    </atom>