function IsEmpty(s){return (s.length==0)}
function IsNum(n){return /^-?\d+\.?\d*$/.test(n)}
function IsInt(n){return (/^-?\d+$/.test(n)&&n.length<=10)}
function IsDate(d,m,y){return (IsInt(d)&&IsInt(m)&&IsInt(y))&&!((d<1||d>31||m<1||m>12)||(d==31&&(m==2||m==4||m==6||m==9||m==11))||(d==30&&m==2)||(d==29&&m==2&&(y%4!=0||(y%100==0&&y%400!=0))))}
function IsEmail(s){return /^[\w\.-]+\@[\w\.-]+\.\w+$/.test(s)}
function HasLength(s,m,M){return (s.length>=m&&s.length<=M);}
function FirstIsLetter(s){return /^[a-zA-Z]/.test(s)}
function Warn(f,m){alert(m);f.focus();return false;}