Hi,
In mechanical drawing terms trailing zeros DO have a value. BS8888 (was BS308) gives the range, generally none = +/- 0.5mm, one = +/- 0.25mm, two = +/- 0.1mm. All drawings (in this company anyway, in the UK) are to BS8888 with the trailing zeros giving generalised tolerances, specifics (fits) are covered with individual marked tolerances per dimension, this keeps a complicated drawing simpler.
The precision option sets the drawings general rules, and with us at least, no drawings are produced without the precision option, any drawings without are not valid and only regarded as rough sketches.
Mike.