Chapter 3. Hooks, Actions, and Triggers, Page 36

Location on the page: 
4th chunk of example code at bottom of page
Chapter: 
3. Hooks, Actions, and Triggers
Error: 

function hook_nodeapi(&$node, $op, $a3=NULL, $a4=NULL) {

Correction: 

function beep_nodeapi(&$node, $op, $a3=NULL, $a4=NULL) {

Description of the Error: 

The function name should be "beep_nodeapi" rather than "hook_nodeapi". The hook itself is named hook_nodeapi(). The hooked version for the module needs to be name [module name]_nodeapi().