function changeDateType(button, form, init)
{
  var color = '#CCCCCC';
  if (button.value=='alt1' || init==1) {
    form.vom2.value='';
    form.vom2.disabled=true;
    form.vom2.style.backgroundColor = color;
    form.bis2.value='';
    form.bis2.disabled=true;
    form.bis2.style.backgroundColor = color;
    form.intervall.disabled=true;
    form.intervall.value=7;
    form.vom1.disabled=false;
    form.vom1.style.backgroundColor = '';
    form.bis1.disabled=false;
    form.bis1.style.backgroundColor = '';
    if (init!=1) { form.vom1.focus() };
  }
  else {
    form.vom1.value='';
    form.vom1.disabled=true;
    form.vom1.style.backgroundColor = color;
    form.bis1.value='';
    form.bis1.disabled=true;
    form.bis1.style.backgroundColor = color;
    form.vom2.disabled=false;
    form.vom2.style.backgroundColor = '';
    form.bis2.disabled=false;
    form.bis2.style.backgroundColor = '';
    form.intervall.disabled=false;
    form.vom2.focus();
  }
}
function checkEmail(form)
{
  if (form.email.value.length == 0) {
    alert('Bitte E-mail-Anschrift angeben !!!');
    form.email.focus();
    form.email.select();
    return false;
  }
  var str = form.email.value;
  var reg1 = /(@.*@)|(\.\.)|(@\.)|(\.@)|(^\.)/;
  var reg2 = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?)$/;
  var reg3 = /@t-online.de$/;
  if (reg1.test(str) || !reg2.test(str)) {
    alert('Bitte E-mail-Anschrift korrekt angeben !!!');
    form.email.focus();
    form.email.select();
    return false;
  }
  return true;
}