lispdoc - results for *debugger-hook*

Variable: This is either NIL or a function of two arguments, a condition and the value of *DEBUGGER-HOOK*. This function can either handle the condition or return which causes the standard debugger to execute. The system passes the value of this variable to the function because it binds *DEBUGGER-HOOK* to NIL around the invocation.
 Mentioned in:
CLtL2 - 29.4.11. Debugging Utilities
PCL - other uses for conditions