@Joe Nation,
Joe: The second one seems to have two uses for the same symbol. The first use is obviously speech, the second could be a number of things to an ESL reader.
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It is only a problem to ESLs when and if they have been given the twaddle that Spendius mistakenly thinks is important.
But that should illustrate to you a truly important point about language and how it really works. We don't learn language from these silly rules. These silly rules have no effect on native speakers because they are, you'll hear or read this soon, alien to the workings of language.
The only ones who know these are those who read Fowler and others like him and even they can't remember to follow these silly rules, because, again, they are alien to the natural rules of English.
If they were real, ie. natural, people wouldn't break them and they never would have to be taught. But sorry for telling you the ending.