It seems in Philippines the vehicles are not equipped with DRL (daytime running lamps), so there it no way to separate a flashing of lights to flashing of brights. I just know to look out because an idiot is gonna take my lane and/or push me over no matter the right of way. To my education (USA and driving abroad) as for horns, short taps are for alerts of both courtesy and attention. Long toots are, well i think there is only one reason for that.
For horn honking, don't forget the people down the street, who, instead of getting out of the car for probably needed exercise, will honk several times for the staff to drop what they are doing and open the gate. ??? When several neighbors do it several times a day, .. And i never saw this in any handbook...