You are working with defines/enums, which are defined in sourcemod\scripting\include\core.inc
PHP Code:
/**
* Specifies what to do after a hook completes.
*/
enum Action
{
Plugin_Continue = 0, /**< Continue with the original action */
Plugin_Changed = 1, /**< Inputs or outputs have been overridden with new values */
Plugin_Handled = 3, /**< Handle the action at the end (don't call it) */
Plugin_Stop = 4 /**< Immediately stop the hook chain and handle the original */
};
So you might as well use these numbers as return values, if you want your code look obscure.
I bet that the timers would just have an if like: "if(bla == Plugin_Stop) ... else...", so it's possible that any other value than 4 might serve your needs.