How to define layout in MODO config so it's available by key to the layout.window command. Snatched from Funk example on MODO slack channel.

layoutWindowConfigExample.CFG

    <atom type="Frame">
        <hash type="Layout" key="base.mbUVSingle_Layout" val="viewportGroup">
            <atom type="IdealSize">1323 875</atom>
            <list type="Port">UVmodel 0 1 0 1 TemplateUV_View</list>
            <atom type="SwitcherClass">normal</atom>
            <atom type="UserName">Mario UV</atom>
        </hash>

        <hash type="LayoutWindow" key="mbUvWindow">
            <atom type="Title">Mario UV</atom>
            <atom type="Contents">(layout) mbUVSingle_Layout</atom>
            <atom type="Size">900 600</atom>
        </hash>
    </atom>