[AccessD] Interfaces -- WAS Access XP forms bound to ADO recordsets

All objects have an implicit, or default interface. It is the set of
property and method calling definitions (or signatures) for the object. 

Interfaces are nice because they allow the compiler check for calling
compliance beforehand, and not wait until runtime to find out that a
method was misspelled, or the wrong number of parameters given.

Explicit interfaces are helpful with polymorphism -- when many objects
need to assume one role, or one object needs to assume many roles. 

Many objects can implement a single interface, and thus provide services
in a standard way to a consumer. Similarly, one object can implement
many interfaces, and so fulfill many roles. 

Interfaces aren't as flexible as inheritance -- when an object
implements an interface, it gets just the property and method
signatures, but not any functionality. Each object must fill in the
interface with its own functionality. Also, you get the whole interface
-- you can't just implement the bits you like.

While a minor part of the .NET object specification, interfaces are the
cutting edge of object sophistication in VBA. And so it will remain --
VBA is a dead language, and will in not too many years be looked back on
like Algol, or maybe Fortran.

-Ken