| **Navigation:**  [[introduction.htm|Language Reference]] > [[chapter runtime properties.htm|App C - PROP: Runtime Properties]] > Complete Property List >====== PROP:FatalErrorHook ====== | [[prop exeversion.htm|{{btn_prev_n.gif|Previous page}}]][[chapter runtime properties.htm|{{btn_home_n.gif|Return to chapter overview}}]][[prop filedialoghook.htm|{{btn_next_n.gif|Next page}}]] | | || A property of the SYSTEM built-in variable that sets the override procedure for the internal Clarion procedure. Equivalent to {PROP:LibHook,9}. Assign the ADDRESS of the overriding procedure, and the runtime library will call the overriding procedure instead of the internal procedure. Assign zero and the runtime library will once again call its internal procedure. The overriding procedure's prototype must be exactly the same as the internal procedure's (STRING message,UNSIGNED ErrorNumber). (WRITE-ONLY)