function presiono_enter(vlr,cant)
{
	netscape  = ""; 
	ver       = navigator.appVersion; 
	len       = ver.length; 
 	for( iln = 0; iln < len; iln++ ) 
	{ 
	   if( ver.charAt( iln ) == "(" ) 
		break; 
	} 

	k = ( netscape ) ? DnEvents.which : window.event.keyCode; 
	if ( k == 13 ) 
	{ 
	 if(isNaN(vlr))
	  { 
	   alert('Valores numericos unicamente');
  	   return false;
	  }
	else
	 {
	  if(vlr<1 || vlr>cant)
	  {
	   alert('La pagina solicitada no existe');
	   return false;
	  }
	 }
	 return true;
	}
}