Hi Jeong,

If you are interested in using the commands defined in the old t-rsteps.tex for showing formulas or text step by step, below is an example I use (it works with mkii and mkiv). The input file I  use can be found here
	http://dl.dropbox.com/u/4316076/t-rsteps-ok.tex
but I attach it also to this message. 
The old « raw steps » is handy when one may need to go backward in the steps or when you want to show, say, the third line of your formula before the second line, but it has the disadvantage of creating one page per step.

\starttext

\setuppapersize[S6][S6]
\setuppagenumbering[state=stop]
\input t-rsteps-ok.tex
\setupinteraction[state=start] 
% uncomment the following when not needing teps
% \UseStepsfalse
% when using \UseStepstrue, we redefine \placeformula...
\ifx\UseStepstrue{\def\placeformula[#1]{\PlaceFormula[#1]}}\fi

\StartSteps[Formula with steps]

\startformula
\startalign
\Step{1}{\NC T(4) \NC = T(3) + 4 \NR} 
\Step{2}{\NC \NC= T(2) + 3 + 4 \NR}
\Step{3}{\NC \NC= T(1) + 2 + 3 + 4 \NR}
\Step{4}{\NC \NC= 1 + 2 + 3 + 4 = 10 \NR}
\stopalign
\stopformula
\StopSteps
\stoptext

Best regards: OK