<svg width="800" height="600" xmlns="http://www.w3.org/2000/svg">
    <title>There should be two green squares.</title>
    <defs>
        <filter id="filt">
            <feColorMatrix values="0 0 0 0 0
                                   1 0 0 0 0
                                   0 0 0 0 0
                                   0 0 0 1 0" />
        </filter>
        <filter id="filt2">
            <feColorMatrix type="matrix" values="0 0 0 0 0
                                                 1 0 0 0 0
                                                 0 0 0 0 0
                                                 0 0 0 1 0" />
        </filter>
    </defs>
    <rect x="0" y="0" width="100" height="100" fill="red" filter="url(#filt)"/>
    <rect x="120" y="0" width="100" height="100" fill="red" filter="url(#filt2)"/>
</svg>