I was thinking about this recently whilst copying files from Microsoft Word to HTML web format then having to test the website in different browsers to see if the 66 & 99 copied properly. This also applies to curved apostrophes and elongated dashes but I wondered how many other punctuation marks are effected.
If you don't know what I'm referring to the 66 and 99 represent the types of double quotation marks. In the days of typewriters and early computers there was just one key to represent the double quote and it would always display as straight quotes. (Shift 2 on a standard UK keyboard). Modern computers still work the same way, but Microsoft Word cleverly detects whether the double quote should be a 66 or 99 then displays the correct character within the font selected. So instead of straight double quotes" you get 66“ and 99” accordingly.
As I already mentioned this also applies to the single quote or apostrophe and also the length of a dash. So it's something to look out for when copying one format to another. So far I haven't noticed any other changes but I'm sure there could be a lot that I simply haven't noticed yet. It doesn't bother me too much but I like consistency when it comes to that kind of thing.
Incidentally I once saw a poster advertising a pantomime that contained both a straight and curved apostrophe within the same banner. I wondered if I would have noticed before I started writing books.