function check_acrobat(pdf_file) {
  if (!confirm("You must have Adobe Acrobat Reader installed on your computer to continue.")) {
    linkto_adobe()
  }
  else { 
    window.open("/literature/" + pdf_file + ".pdf", "")
  }
}

function linkto_adobe() {
  if (confirm("Download Adobe Acrobat Reader now? (It's free.)")) {
    window.open("http://www.adobe.com/products/acrobat/readstep.html", "")
  }
}

function open_window(url_name) {
  var window_height = 400
  var window_width = 600
  var window_dimensions = "height=" + window_height +
                          ",width=" + window_width +
                          ",top=80,left=40,resizable,scrollbars"
  window.open(url_name, "", window_dimensions)
}

function no_data(cur_field, fld_label) {
  if (cur_field.value == "" || cur_field.value == null || 
         its_whitespace(cur_field.value)) {
	cur_field.focus()
    alert('"' + fld_label + '" is a required field.')
    return true
  }
  return false
}

function its_whitespace(string_val) {
  var whitespace = " \n\r\t"
  for (var counter = 0; counter < string_val.length; counter++) {
    cur_char = string_val.charAt(counter)
	if (whitespace.indexOf(cur_char) == -1 ) {
	  return false
	}
  }
  return true
}