// exemplo do uso
// <input type=text name=txtCpf size=11 maxlength=11 onblur="return CPFCNPJOK("SSCPF")">

function ck_soNum(pCampo)
{
    var charCode        = (navigator.appName == "Netscape") ? event.which : event.keyCode;
    var var_caracter    = String.fromCharCode(charCode);
    if ((var_caracter>="0") && (var_caracter<="9"))
    {
        return true;
    }
    else
    {
        return false;
    }
}