Events are passed with parameters. It's more efficient to specify exactly what you want and allow the engine to filter these for you, rather than hooking the event and then making those checks yourself.
From amxmodx.inc:
PHP Code:
/* Registers event on which a given function will be called
* Flags:
* "a" - global event.
* "b" - specified.
* "c" - send only once when repeated to other players.
* "d" - call if is send to dead player.
* "e" - to alive.
* NOTE: Due to a long-standing bug that would break compatibility with old plugins,
* the client id should be checked for alive/dead state if you use d or e.
* Examples for conditions:
* "2=c4" - 2nd parameter of message must be sting "c4".
* "3>10" - 3rd parameter must be greater then 10.
* "3!4" - 3rd must be different from 4.
* "2&Buy" - 2nd parameter of message must contain "Buy" substring.
* "2!Buy" - 2nd parameter of message can't contain "Buy" substring. */
native register_event(const event[],const function[],const flags[],const cond[]="", ... );