Cris, as I read it...the range for the wrench in my "addendum" above is 250-50=200...then 20% of 200 is 40...so, consider the first 40 ft-lbs "unuseable", which when added to the 50 ft-lbs starting point means that we can consider a reading of 90 ft-lbs as the LOW END of the accurate readings, thus useing 90 ft-lbs and above with the reasonable accuracy of +/- 4% as stated.
Respecting this concept will save much grief...while it is old stuff to the more experienced folks, I do believe that the concept is often lost in the fine print while making a purchase...to say nothing of the need to recalibrate said wrenches on a regular basis depending on usage.
Cris, I see your point, but I reason that the stated caution by the manufacturer would have no bearing whatsoever in the case you propose as you cannot use a torque setting NOT stated on the wrench, such as 46 or 32 or any other below the 50...and therefore, feel that the verbage in the warning means RANGE of the markings. So, I (right or wrong) do the calculation, and use the wrench that fits the numbers for the job.
ADDENDUM: Cris, I just hauled out of of my wrenches...in this case, the scale on the wrench is inscribed 5-75 ft-lb.
PLEASE NOTE that the RANGE stated at the top of the Certificate of Calibration states the "Range" as "15.00-75.00 ft-lb"...IGNORING, if you will, the first few markings at the low end of the scale printed on the wrench.
I KNOW that my long and wordy attempt to explain all of this may be lacking...so hopefully someone else can chime in to help. Too bad that I cannot currently find the actual plot of this accuracy situation on the Snap-On site, though I do have it in a 4-5 year old catalog...and, have found the same general numbers on the Sears Craftsman site in the past year or so.