You have to have read the RFCs that define URLs with a pretty sharp eye to have spotted this one. What it means is that if you have <a href='Start#part1'>, then part1 isn't part of the URL. But if you have <a href='Start?q=a23'>, then q=a23 is part of the URL.
This means you can do things like <a href='Start?q=a23#part1'>, but it means that you really can't use an address containing a # to refer to an external entity.
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