Why can't RSS handle the ampersand?

Question

When I come across a broken RSS feed, the usual reason its all blown to pieces is because line 23 says "Sanford & Sons."

The most confusing thing is the fact that if you convert the & into &, all is well, even though your alternative still contains the problem character.

Why does RSS fail at rendering the ampersand (&) character by default?

Answer 1

When a 'raw' & is seen, the interpreter is looking for one of the valid escaped & sequences (such as '&' ). When an invalid sequence is found it throws an error. That's all there is to it.

Answer 2

Because rss is an XML-based format and in xml the ampersand (&) signifies the start of an xml entity. The parser is expecting something else there.

You could argue that it should be smart enough to know that the ampersand in "Sanford & Sons" is just an ampersand. But what about when you really want to show ampersand with text? Is "&pc; some custom (also invalid) entity, or should it interpret that as an ampersand also? What about "&"?