function SoNumeros(e, objeto){

	var keynum
	var keychar
	var keyspecial
	var numcheck
	campo = eval (objeto);
	
	if(window.event){
		keynum = e.keyCode
	} else if(e.which) {// Netscape/Firefox/Opera
		keynum = e.which;
	} else if ((e.which == 0) || (!window.event)){
		keyspecial = e.keyCode
	}

	keychar = String.fromCharCode(keynum)
	numcheck = /\d/

	if (numcheck.test(keychar) || (keynum == 8) || (keyspecial == 9)) {
		return true;
	} else {
		return false;
	}
}