Explain in ref man that exporting an obj does not automtatically export the
    types of its components and similarly, exporting a op does not
    automatically export the types of its args.  But, exporting an op does
    export all overloads of that op.

(Perhaps) allow order of imports and exports to be unconstrained.
Eliminate plural spellings "preconditions" and "postcondtions" as keywords;
    they're imprecise and misleading.
In the maybe rewrite, consider not doing the separate namelist flattening
    during type checking.  It seems to be obsolete typecheckingwise.  However,
    it may still be necessary browserwise.  Anyway, check it out.
Do type checking for newly added fixed-length lists.
    STATUS: DONE, but then removed.  See 1jun00 LOG entry.
More fully test def of and access of multi-arg op outputs, per 2mar00 LOG
    entry. 
Organize option flags to turn things like '::=' and unionizing multiple obj
    decls off; here's a thought -- only unionize when '::=' is used instead of
    'is'.
Change "instance of" to "inherits from".
    STATUS: DONE, but left "instance of" for backward compatibility.
Do what's supposed to happen for sym lit types, viz. on the 1st occurance of a
    sym lit, an opaque type is entered in level 0 for it.
Enhance syntax and type checking "in" form of quantifier clause to allow var
    list, as in "forall (i,j in [1..#l]) ...".
Add "implementation" as a new built-in op attribute that has the same value
    as what follows the '=' in an op def.  Handle just like we handle
    short-form obj's with ``is'' vs explicit ``components'' attribute.
Allow importation of and inheritance from overloaded ops.
Make obj from op decl.
Make constructor op from obj decl.
Type check overloadings of built-in operators.
Finish checking that prohibits functions with identical args.
Finish resolution of op inheritance.
(Finish) implement(ation) of concrete object type checking; see in particular
	tests/concrete-objs.rsl.  Be sure to include check that the value expr
	in a concrete obj def is a constant expr.  Initial thougts are that
	this check needs to be done in pass 2.
Allow multiple obj decls and unionize them; see thoughts on this subject in
	rsl3/doc/implementation-ideas.me.
Implement any (remaining) missing parts of the new spelling-based type checking
	alg.
Implement where clause processing.
    STATUS: Done except for op types.
Implement type checking of action attributes.
Implement "relation" keyword as adjunct to "attribute".
Allow pre/postconds in obj defs.
Finish auto or'ing of redef'd objects.