Customer writes:

The javadoc for java.util.regex.Pattern indicates that character class
subtraction is done by a combination of intersection and negation:

[a-z&&[^aeiou]]

Then later in the same table, it indicates that named character classes
can be subtracted with a hypen. The example give is:

 [\p{L}-[\p{Lu}]] Any letter except an uppercase letter
                    (subtraction)

I suspect this is a syntax error, and my experiments with the
implementation confirm it. I think the example should be written using
&& and ^ instead of -.

The javadoc for Pattern says this:

    (?idmsux-idmsux:X) X, as a capturing group with the given flags on -
off

But the Perl documentation says this:

    (?imsx-imsx:pattern)
This is for clustering, not capturing; it groups
subexpressions like "()", but doesn't make
backreferences as "()" does. So

I suspect there is a typo in the javadoc, and it should say
non-capturing instead of capturing.