function Trim(st)
{
	var dat, i, j1 = 0, j2 = 0;

	if(st.length == 0) 
		return "";
	if(st.length == 1){
		if(st.charAt(0) == " ")
			return "";
		else
			return st;
	}

	for(i=0;i<st.length;i++){
		if(st.charAt(i) == " ")
			j1++;
		else
			break;
	}
	if(j1 == st.length) 
		return "";

	for(i=st.length-1;i>=0;i--){
		if(st.charAt(i) != " ") {
			j2 = i;
			break;
		}
	}
	return st.substring(j1,j2+1);	
}

function checkMail(cadena) {
	var plant =/(^\w+)([.-](\w+))*[@](\w+)([.-](\w+))*[.]([a-z0-9]){2}([a-z0-9])?$/i;		
	if (plant.test(cadena))		// es correcta
		return true; 
	else 					// no es valida
		return false; 
}

function checkFecha(cadena) {		// dd/mm/aaaa
	var plant =/^\d?\d\/\d?\d\/[\d]{4}$/i;		
//	var plant =/^\d\d?\/\d\d?\/[\d]{4}$/i;		
	if (plant.test(cadena))		// es correcta
		return true; 
	else 					// no es valida
		return false; 
}