-;;; We have a separate COMPILER-ERROR condition to allow us to
-;;; distinguish internal compiler errors from user errors.
-;;; Non-compiler errors put us in the debugger.
+;;; an application programmer's error caught by the compiler
+;;;
+;;; We want a separate condition for application programmer errors so
+;;; that we can distinguish them from system programming errors (bugs
+;;; in SBCL itself). Application programmer errors should be caught
+;;; and turned into diagnostic output and a FAILURE-P return value
+;;; from COMPILE or COMPILE-FILE. Bugs in SBCL itself throw us into
+;;; the debugger.