well, u see,
you can put things like blue etc in the brackets, however, using numbers is much more efficient and lets u do more things.for eg., check the program below,
writeln('enter 0 for all values to exit');
writeln('what text color do you wish to see?);
writeln('what back ground color do you wish to see?');
writeln('what sound do you wish tpo hear?');
UNTIL (snd=0) AND (col=0) AND (bkg=0);
this program would be very complex if u uses words like blue etc.
does this help?