[plt-scheme] On PLaneT packages and compatible upgrades

Doug Orleans writes:
 > The language specification spells out in great detail which changes to
 > a package, class, or interface preserve "binary compatibility" and which
 > do not.  In particular, adding a new class and adding a new method to
 > an existing class do not.

Oops, I meant, "do not break binary compatibility".  Sorry for any confusion.

--dougorleans at gmail.com