var state_0 = false;
var state_1 = false;
var state_2 = false;
var state_3 = false;

function alterState(val, state) {
	switch(val) {
		case '0' :
			state_0 = state;
		break;
		case '1' :
			state_1 = state;
		break;
		case '2' :
			state_2 = state;
		break;
		case '3' :
			state_3 = state;
		break;
	}
}

function expCol(state, val) {
	if (state) {
		document.getElementById("lyr_" + val).style.display = "none";
		state = false;
	} else {
		document.getElementById("lyr_" + val).style.display = "inline";
		state = true;
	}
	alterState(val, state);
}