The primary showing no trailing zeros is per the ASME Y14.5M spec. for metric dimensioning.
My guess is that your 20 is actually between 19.995 and 20.005, therefore rounded to 2 decimal places gives 20.00, then apply Y14.5 to get 20 . The secondary is to the max display, which indicates that the dimension is driven from an intent dimension rather than a fixed dimension.
Thank you,
Ben H. Loosli
USEC, INC.