Thread: Quick question about a block of code

I found this in a source file I was looking at for a navigation system for an RC plane. What is the "ISR(PCINT2_vect) {"? Is it a function?... and if so what is the significance of having just a single type in the parameters?

Code:

#if RADIO_TYPE == 0
ISR(PCINT2_vect) {
	int cnt = TCNT1;
	
	if(PIND & B00000100){ 		// ch 1 (pin 2) is high
		ch1_read = 1;
		timer1count = cnt;
	}else if (ch1_read == 1){	// ch 1 (pin 2) is Low
		ch1_read = 0;
		if (cnt < timer1count)   // Timer1 reset during the read of this pulse
		   timer1diff = (cnt + 40000 - timer1count);    // Timer1 TOP = 40000
		else
		  timer1diff = (cnt - timer1count);
	}
	
	if(PIND & B00001000){ 		// ch 1 (pin 2) is high
		ch2_read = 1;
		timer2count = cnt;
	}else if (ch2_read == 1){	// ch 1 (pin 2) is Low
		ch2_read = 0;
		if (cnt < timer2count)   // Timer1 reset during the read of this pulse
		   timer2diff = (cnt + 40000 - timer2count);    // Timer1 TOP = 40000
		else
		  timer2diff = (cnt - timer2count);
	}
}
ISR(PCINT0_vect)
{	
	int cnt = TCNT1;
	if(PINB & B00100000){
		timer3count = cnt;
	}else{	
		if (cnt < timer3count)   // Timer1 reset during the read of this pulse
		   timer3diff = (cnt + 40000 - timer3count);    // Timer1 TOP = 40000
		else
		  timer3diff = (cnt - timer3count);
	}
}
#endif

ISR presumably = Interrupt handler. Either you have a bespoke compiler that is tailored to whatever chip you're looking at that handles the low-level stuff, or someone's been doing some #define magic.