Thank you for the link, the answer to my question was as in the example you gave, but with a single argument. The solution to my problem given below works, but I can't find the answer to the following question. What is the difference between \dosingleempty and \dosingleargument ?

%%%%%%%%%%%%%%%%%%%%%%%
\unprotect

\definesystemvariable {dt}

\def\setuptitle
  {\dosingleempty\dosetuptitle}

\def\dosetuptitle[#1]%
  {\def\dodosetuptitle##1%
     {\getparameters[\??dt][#1]}%
  \processcommalist[#1]\dodosetuptitle}

\def\placetitle
  {\startalignment[\v!middle]
   \blank[\v!force,2*\v!big]
   \@@dttitle
   \blank[3*\v!medium]
   \@@dtauthor
   \blank[2*\v!medium]
   \@@dtdate
   \blank[3*\v!medium]
   \stopalignment}

\setuptitle
  [\c!title=,
   \c!author=,
   \c!date=\currentdate]

\protect
%%%%%%%%%%%%%%%%%%%%

On Fri, Feb 5, 2010 at 11:29 AM, Wolfgang Schuster <schuster.wolfgang@googlemail.com> wrote:
Am 05.02.10 09:03, schrieb Marius:

Hello all,

How do I define the \setuptitlepage and \placetitlepage commands in the
environment file? These commands are used as shown in the example below.

Since you do not explain what do you expect from both commands it's not possible to give you an answer but you can find on the wiki [1] a example for a \setuptitle and \placetitle command which can be copied and used in your document.

[1] http://wiki.contextgarden.net/Document_Titles#In_ConTeXt:_A_more_advanced_solution

Wolfgang