Can anyone tell me what the maximum length of an HTML form field "name" attribute is?

What I've discovered is that this form field is ok:

<input name="1234567890123456789012345678901234567890123456789012345678901234" type="text" size="30" maxlength="30" value="">

But that this isn't ok:

<input name="12345678901234567890123456789012345678901234567890123456789012345" type="text" size="30" maxlength="30" value="">

The difference is that the first example has a Name attribute that is 64 characters long and the second has a Name attribute that is 65 characters long.

On a web server that I use that's running Apache 2.2.3 the first works and the second fails, so it looks like the maximum length you can have is 64 characters.  But on another web server that I use that is running Apache 2.2.4 both examples work ok.

I've tried looking on the Apache site to see if this is specified anywhere but I'm not familiar with the site and I can't seem to find any documentation about this.  Can anyone comment?