Cocher / décocher checkbox

You can use this script as the Mouse Up event of "ERP", for example:

var otherFieldNames = ["PA", "CTS", "PYRO"];
if (event.target.value=="Off") {
	for (var i in otherFieldNames) this.getField(otherFieldNames[i]).readonly = false;
} else {
	this.resetForm(otherFieldNames);
	for (var i in otherFieldNames) this.getField(otherFieldNames[i]).readonly = true;
}

Adjust the first line and re-use the code for the other fields.