Perhaps the most interesting or important is: all of heraldry. One might initially think that is rather remote from logos, but it is really a principal root of

Perhaps the most interesting or important is: all of heraldry. One might initially think that is rather remote from logos, but it is really a principal root of them. Heraldic devices -- 'armorial bearings' (particularly) -- are defined abstractly, in clear conceptual forms, leaving the rendering details unspecified. (Heraldry also developed a graphical serialisation standard long before, and in a way more elegant than, SVG-XML etc.) It might be 500 years old, but it still has something to learn from.