This (as well as what Hans suggested) takes care of the first case. But
I also what it to print

Definition 1 (Name)    Bla Bla..

when I type

\startdefn[ref]{Name}
Bla Bla ..
\enddefn

i.e., when I supply the "Name" option to defn it should print "(Name)"
right after "Definition 1" and then leave some spacing (the amount that
it would have left normally). Just like

\begin{defn}[Name] \label{ref}
Bla Bla
\end{defn}

would have worked in LaTeX if I had 
\newtheorem{defn}{Definition}

I would also like to use this to
generate a table of definitions (of those definitions which had an
option).

Tar{\i}k

On Thu, 5 Jul 2001, Eckhart [iso-8859-1] Guthöhrlein wrote:

> At 12:50 05.07.2001 +0300, you wrote:
> >How can one define a numbered definition environment (say "defn") which
> >works like:
> >
> >Prints:
> >
> >Definition 1      Bla Bla Bla
> >
> >when one uses
> >
> >\startdefn[ref]
> >BLa Bla Bla
> >\stopdefn
> >
> >but prints:
> >
> >Defintion 1 (Name)     Bla Bla Bla
> >
> >when one uses
> >
> >\startdefn[ref]{Name}
> >Bla Bla Bla
> >\stopdefn
> >
> >i.e., an environement which works like the Theorem environment of LaTeX.
> >Thanks.
> >
> >Tar{\i}k
> 
> You can adapt this:
> 
> \defineenumeration
> [guess]
> [text=Conjecture,
> location=left,
> letter=it]
> \starttext
> This is the first one:
> \guess All conjectures are interesting.
> 
> This is the second one:
> \startguess Except this one.\stopguess
> \stoptext
> 
> I have taken this from 'LaTeX in proper ConTeXt' by Berend de Boer, a 
> document you will probably be interested in. It is available here:
> http://tex.loria.fr/formats/context/LaTeX2ConTeXt.pdf
> 
> Eckhart
> 
>