On Jun 17, 11:47*pm, Steve Ackman
wrote:
...
* On submarines, for anything less than 6",
a three place decimal is +/- .005"
Two place decimal is +/- .010"
Fractional dimensions are +/- 1/64"
...

http://en.wikipedia.org/wiki/Tolerance_(engineering)

When I was a paper & pencil draftsman the title block tolerance was
0.005" for three places, 0.020 for two, unless otherwise specified. I
think they applied for aerospace parts at MITRE, though there I
usually drew my own title blocks on the CAD system and negotiated
tolerances with the vendor, to get as much as I could without paying
extra.

jsw