Tests for proper handing of XML:

Following are common errors often found in XML that SHOULD cause an aggregator to flag the feed as not well formed:


[AsbjornUlsberg] [AnswerMe:] Could you please try to give some examples and solutions (either by writing it here, or by linking to some website that does it) for each of the cases mentioned above? It would be easier to understand the problems if they were examplified.