I warn you, send your child to bed before reading this code snippet:
<span id="lblUser Birthday">User Birthday</span><br> <input type="text" name="txtUser Birthday" ID="txtUser Birthday">
OK, the HTML4 DTD allows spaces inside the NAME attribute (it’s a CDATA) but it’s one of the worst practices I ever saw (even the control’s name autogenerated by ASP.NET web forms uses $ to separate names’ parts).
And spaces are not allowed inside the ID attribute.
Pragmatists would say that IE and Firefox are pretty tolerant and eat up everything, but this is pretty scary anyway.
I didn’t dare to ask “Who wrote this code?!”