function check_top()
{  
    flag=true;
    errmsg="";	
	var docf=document.frm_login_top;
	var cnt=0;
	if(docf.usrname.value=="")
    {
		alert("Please enter Username.");
		docf.usrname.focus();
		return false;
	}
	if(docf.usrname.value!="")
	{
		val = docf.usrname.value;
		newVal = '';
		val = val.split(' ');
		for(var c=0; c < val.length; c++) 
		{
			
			if(isWhitespace(val[c].substring(0,1)))
			{
				alert("Please enter correct username.");
				docf.usrname.focus();
				return false;

			}
		 }
	}
	if(!isAllCharacters(docf.usrname.value))
	{
		 alert("Please enter correct username. ");
		 docf.usrname.focus();
		 return false;
	}
	if(docf.password.value=="")
    {
		alert("Please enter Password.");
		docf.password.focus();
		return false;
	}
}