what is the difference between "timer=1" and "timer=0"?

In fact, I do not understand what the expression "timer=n" means for an arbitrary integer in Singular. After I use "timer=1", I test the value by typing "timer;" but to get "0".　Any one can give me some tips about it? Thank you in advance!

See http://www.singular.uni-kl.de/Manual/4-0-1/sing_447.htm.
Remember that assigning a value to timer means setting a certain switch on (if not 0) or off (if 0)
while reading a value from timer is the cpu time: it has nothing to do with any assigned value.

Thank you very much for your kind help! :D