asciidoc 7--8 compatibility (was Re: pull-fetch-param.txt)

Stuart Rackham wrote:

Stuart,

the actual issues were:

1.) Input which works with asciidoc 7 fails to build with asciidoc 8 (after the intermediary XML step). This pair of tildes broke (but other occurences of tilde did not):

| * A suffix '~<n>' to a revision parameter means the commit
|   object that is the <n>th generation grand-parent of the named
|   commit object, following only the first parent.  I.e. rev~3 is

2.) Asciidoc 8 silently swallows characters from input which works with asciidoc 7. The two pluses in the following line vanished (but instances of single pluses per input line did not vanish):

| 	`+?<src>:<dst>`; that is, an optional plus `+`, followed

I wonder:

 - Are tilde and plus new special characters in asciidoc 8, or were they
already special characters in asciidoc 7?
       [ A pair of single pluses encloses monospaced text in asciidoc 8.
         A pair of single tildes encloses subscripts. ]

 - If they were already special characters in asciidoc 7, what is the
canonical way to escape them in asciidoc 7, 8, and hopefully 9?
       [ If they weren't special characters in asciidoc 7, then we need
         to use the asciidoc7compatible attribute. ]

 - Does asciidoc 7 accept the asciidoc7compatible attribute?

Thanks.

PS:

Junio, Stuart, here is another inconsistency between asciidoc 7 and 8.
Please have a look at
http://www.kernel.org/pub/software/scm/git/docs/git-rev-parse.html .
See the ASCII art above "SPECIFYING RANGES". The input
       \  |  / \
        \ | /   |
produced
   \  |  /         \ | /   |
I.e. backslash-newline was interpreted by asciidoc 7 (or whatever you
use to generate what is put online) as an escaped thus swallowed
newline. But the output that I got here from asciidoc 8 (manpage as well
as the html file) still has backslash and newline printed out.