Thanks for the reminder.
Some questions about 'rulers':
1) Would you expect to see measurements on the horizontal and vertical axes of these rulers (e.g. 1m, 2m etc.)?
2) Would you expect to drag out a position on the ruler to show a vertical/horizontal guideline on the drawing? If so, is 1 guideline sufficient or are you looking for multiple guidelines in each axis?
3) What other specific functionality, if any, do you seek from 'rulers' because that term can be interpreted in several ways? What is the problem you're trying to solve with a ruler?