The browse command used to have a required parameter id=... and it returned
info on the given identifier only. Now, if format=json, the id=... parameter
can be omitted to get info on all identifiers at the same time. The returned
JSON structure in this case is
{cats:{...},funs:{...}}
where the inner objects contain one field per category and function,
respectively, in the same format as when you request info on one category or
function.