QEV, (Quote Entity Validator) Validates HTML, with specialised checks on
HTML syntax to make sure double and single quotes are balanced.
1. makes sure “ ... ” (double quotes) occur in balanced pairs
without nesting.
2. makes sure ‘ ... ’ (single quotes) occur in balanced pairs
without nesting.
3. makes sure &lsdquo; ... ’ (single quotes) occurs only inside a
“ ... ” (double quotes)
QEV does not modify your files, just points out problem areas.
Unfortunately ’ is also used for an apostrophe.  QEV tries to guess
which way you are using ’, but it does not always guess correctly,
(it uses some hairy ad hoc logic) so you will get some spurious error
messages.  One way around this is to convert your apostrophes to something
else temporarily, e.g.  ' then convert them back after you get all
your quotes balanced.  Unfortunately, there is no other character that
looks like a right single quote to encode your apostrophes permanently.
I am lobbying W3C to create one, that maps to the same glyph.
There is a similar problem with ” being also used to indicated feet
or minutes of latitude/longitude.
Tips
****
1. Sometimes QEV will perceive a single error as a
chain of errors, (much the way a Java compiler can be confused).  Just fix
some of the errors, and run QEV again.  Often you will have
cleaned up a number of errors from one change to the source file.
2. Use an editor such as Visual Slick Editr that lets you jump to a given
line number.  QEV tells you the line and column number in the
file where the problem is.
3. Take the error messages with a grain of salt.  Pay more attention to
the spot in the file it is complaining about.
4.  save your changes and rerun QEV often.  It is very quick.
It is easier to work when you have the errors you have already fixed off
the decks.
5. invent a CSS styles like this:
.quoted /* words somebody said, a direct quotation,italicised and surrounded in quotes */{
	font-style: italic;
}
.quoted:after,.asays:after,.bsays:after,.csays:after{
	content: close-quote;
}
.quoted:before,.asays:before,.bsays:before,.csays:before{
	content: open-quote;
}
Then there will be no “ ” in your HTML to balance, and any
HTML validator will ensure your <span call="quoted">...</span> balance.
The few remaining &ldquo; and &rdquo; with be apostrophes not intended to
balance.
You can use option switches on the command line:
-guess  : the default. Guesses which &lsquo; &rsquo; &ldquo; &rdquo; should be balanced.
-ignore : ignores &lsquo; &rsquo; entirely. Use when you are overwhelmed by false balancing errors.
-strict : strictly balances &lsquo; &rsquo; &ldquo; &rdquo; even when some &rsquo;s appear
          to be used as apostrophes and &rdquo;'s as inches/minutes marks.
-British: use the British conventions where double quotes are nested inside single quotes, unlike
the way Americans do it with the single quotes nested inside single quotes.
Running
*******
To validate a single file, type:
  java.exe -jar C:\com\mindprod\qev\qev.jar E:\myhtml\index.html
To validate all the files in a single directory, type:
  java.exe -jar C:\com\mindprod\qev\qev.jar E:\myhtml\
To validate all the files in a single directory tree, type:
  java.exe -jar C:\com\mindprod\qev\qev.jar -guess -s E:\myhtml\
Limitations
***********
Formal English deliberately does not balance double quotes on quotations
spanning several paragraphs.  There is not just an &ldquo; at the
beginning and &rdquo; at the end, but at &ldquo; at the start of each
intermediate paragraph.  QEV does not support that.  It reports the
&ldquo;s at the start of each intermediate paragraph as an error.
You could mollify QEV by putting in dummy &rdquo;s at the ends of he intermediate
paragraphs using a non-displaying style or  in a <!-- ;rdquo --> comment.