It is intended to hold several columns of information for each row of information.
The most obvious example is the table of context members. In a minimal definition, a context simply has a list of members. Should however the context need to add extra information for each member, we need a syntax to deliver this information.
Such extra information could be a speakaction valid only in that chatroom, or it could be a user icon, but it could as well be a routing hint (a multicast router uniform) or an administrative role in the chatroom like _moderator, _speaker or _listener.
Another obvious use is sharing our list of friends with our friends. In order for trust metrics to work immediately using maths applied to the decentralized state, we not only need to know who our contacts and the peers of our contacts are, we also need to know the trust they have given them. This requires at least a two-dimensional table.
The requirements are to be dynamically extensible, to support inheritance on all levels, to be intelligible by any application at least in part (if you don't understand everything in the table, just use what you understand).
See also wikipedia:Table (information)