corplist: please provide documentation

[Ansa211]

It would be great to know which attributes exist and are actually used by KonText so that we remove unnecessary clutter from corplist. E.g. in this setup (from our current corplist.xml on production), I suspect the corpus attributeskeyboard_lang, features and parallel are no longer used anywhere (and possibly never were). Please correct me if I am mistaken.

<corpus ident="summa_la_a" keyboard_lang="en" sentence_struct="s" features="morphology, syntax" access="anonymous"  parallel="default">
        <metadata>
            <keywords>
                <item>parallel</item>
                <item>Summa</item>
                <item>la</item>
                <item>morphology</item>
                <item>syntax</item>
                <item>current</item>
            </keywords>
        </metadata>
    </corpus>
    <corpus ident="summa_cs_a" keyboard_lang="cs" sentence_struct="s" features="morphology, syntax" access="anonymous"  parallel="complement">
        <metadata>
            <keywords>
                <item>parallel</item>
                <item>Summa</item>
                <item>cs</item>
                <item>morphology</item>
                <item>syntax</item>
                <item>current</item>
            </keywords>
        </metadata>
    </corpus>

Another parameter that is set on some corpora and I am not sure whether it is used is howto.