over 
relations and functions. However, it will not actually be 
higher-order. (It is equivalent to a sublanguage of Lw1w which I 
think is compact, but havnt quite proved this yet.) The extensions 
are somewhat murkier than the core, but two of them that have been 
fairly well identified are (1) a sorted extension, in which for 
example argument 'sorts' for functions and relations can be specified 
and will be checkable at parse time; and (2) a meta-extension, which 
will have fully-fledged capabilities fo