Computer traced? Do you mean like by a 
machine? Cels also can have the trace lines 
put on them by a xerox-type machine, the lines 
aren't as dark as hand-traced lines, and 
oftentimes aren't perfect, with little breaks here 
and there. This is the most common method 
used for making cels. Nowadays, they scan 
the sketch into a computer and then darken 
the lines and color the cel, all digitally. 
Sometimes they even draw the trace lines in 
the computer, using the sketch only as a 
reference. Hope this helps.