I just found out that 
  \definenote[afootnote][rule={on,right}]
instead of
  \definenote[afootnote][rule=right]
works and places the footnote rule on the right-hand side.

Still wondering about how to get automatic right/left rules.

On Sun, Jan 3, 2016 at 1:22 PM, Mohammad Hossein Bateni <bateni@gmail.com> wrote:
Hi,

This has been previously discussed on the list but I didn't find a resolution to the issue.  It might as well be my fault since I didn't go through the entire archive and I am needless to say new to CONTEXT.

In a bidi text (Persian/English in my case), I would like the footnote rule to be placed on the right-hand side if and only if the first line of the footnote text is RTL.  Is there a way this information can be obtained within a user-defined rulecommand.  Ideally I'd like a rule=autodir attribute for notes in addition to the current left & right.

Speaking of which, the left & right rules do not seem to work, or I misunderstand their point.  When used (either left or right), the footnote rule disappears.

\starttext

\definenote[afootnote][paragraph=no,rule=right]

\startalignment[r2l]
righttoleft text\afootnote{\input ward }
\input tufte
\stopalignment

\startalignment[l2r]
lefttoright text\afootnote{\input ward}
\input tufte
\stopalignment

\stoptext

I see these defined in strc-not.mkvi and still don't work with "% macros=mkvi" in the first line of the input file and when the file has extension mkvi.  Is this some issue of mkiv vs mkvi?  For what it's worth, I don't notice a reference to MKVI in the compilation output.

Back to the main question, I can define my own rule as follows:

\unprotect
\def\myfootrule{%
 \ifvmode
      \dontleavehmode \hskip.8\hsize\blackrule
        [\c!color=\noteparameter\c!rulecolor,
         \c!width=.2\hsize,
         \c!height=\noteparameter\c!rulethickness,
         \c!depth=\zeropoint]%
      \endgraf
      \kern\strutdepth
    \fi}
\protect

Then I can use

\definenote[afootnote][paragraph=no,rule=command,rulecommand=\myfootrule]

to get a footnote rule on the right-hand side.  If I can figure out whether the first line of the footnote text is RTL or LTR, an if-statement can do the trick I want.

Somewhat related to this, I was wondering whether it's possible to define two note commands, say \footnote and \afootnote, that use the same counter but are otherwise completely different.

I use TeXLive 2015 on Mac OS X,
         CONTEXT 2015.05.18 12:26, and
         LuaTeX, Version beta-0.80.0 (TeX Live 2015) (rev 5238).

Thanks a lot!
—MHB