reduces the possibility of confusion or error in the measurement and calibration process however it is certainly possible within the contemplation of the current invention to have different color schemes for linear measurement as in bars as distinct from area measurement as in rings indeed in alternative embodiments of the current invention colors need not be used each ring need only be visually distinct from each other ring and the same for the bars this could be accomplished by shading cross hatching or other drawing techniques or use of additional visual indicia we make the above point so as to reinforce two important points of the present invention first the color code scheme is not important in and of itself the color red for instance could represent a shorter length wound or a longer one red could represent a small area wound or a larger one the importance is in the standardization of a scheme such that red always means the same length bar or inner area circle or polygon second the linear dimension calibration of the bars is not the same though related dimension as the table i rings provide nevertheless color can and will be standardized and coordinated between the rings and bars example being the red bar can have a value of 5 linear centimeters and the red ring represents 5 sq cm the rings or bars are preferably distributed as sets mounted on a pad in some embodiments there is extra room on each sheet of the pad for writing notes as displayed in fig5 item 300 this could be valuable for instance in dating the calibration or making some other notes to be.