Hi Wolfgang,

Thank you for your attention: in fact you pointed out how to solve the problem… 
Beginning with what you wrote, after a few trials and errors I ended up with the following which gives what I meant:
%%% begin reverse-enumeration.tex
\definenumber[ReverseNumberOrder][numberorder=reverse]

\defineenumeration[Lecture]
[location=hanging,
text={Lecture n° {\convertednumber[ReverseNumberOrder]}.}, 
between=,
before={\incrementnumber[ReverseNumberOrder]},
number=no,
after={\hrule\blank}]

\starttext

\startLecture Tuesday December 6th: Banach spaces. 
\startitemize[n]
\item First subject.
\item Second subject.
\stopitemize
\stopLecture

\startLecture Tuesday November 29th: Norms. 
\startitemize[n]
\item First subject.
\item Second subject.
\stopitemize
\stopLecture

\startLecture Tuesday November 22nd: Topological Vector Spaces. 
\startitemize[n]
\item First subject.
\item Second subject.
\stopitemize
\stopLecture

\stoptext
%%% end reverse-enumeration.tex

Best regards: OK

On 12 déc. 2011, at 14:03, Wolfgang Schuster wrote:


Am 12.12.2011 um 13:33 schrieb Otared Kavian:

Hi all,

When using
\startitemize[n,reverse]
one gets items numbered in reverse order. I wonder if this feature exists also for enumerations. An example is given below in which the last enumeration is written on top of the file and I wish it were possible to have the enumerations numbered in reverse order.

The numbering mechanism has indeed such a option but it seems to be not available for enumerations.

\definenumber[foo]
\definenumber[bar][numberorder=reverse]

\define\test
 {\incrementnumber[foo] \incrementnumber[bar]%
  \convertednumber[foo]:\convertednumber[bar]}

\starttext
\dorecurse{9}{\test\par}
\stoptext

Wolfgang
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