Autocad

Whatever you'd like it to be. It's adjustable.

thanks

If you are referring to the UNITS variable in AutoCAD, you have several options, including:

Fractional (inches and numerator/denominator fractions)

Decimal (either inches or mm, and you can specify how many decimal places)

Architectural (feet and inches/fractions)

Engineering (feet and inches/decimal).

You can also set up alternate dimensions in [...] that can convert inches to mm and vice versa.

Most recently Autocad R14, 2000, 2002,2006,2007,2008,2009 2010, or 2011 are in SI units. Nobody used english system unit in Autocad seemed you are left behind or backward. Most of the paper(roll) used can be plotted in drawings size A-3(297x420mm), A-2(420x594mm), A-1(594X841mm), A-0(841x1189mm). These are the paper sizes standards widely used by Autocad operator/s and as standard site drawing plans, reason why your autocad settings must be in SI... you know why? in contruction/ erection of the buliding,etc... scales for example 1:50 (1m=2cm in drawing scale) and 1:100 (1m=1cm in drawing scale) basically it is much easier for the carpenters/masons/electricians etc. to read the scales in the construction site rather than in english units such as 1-1/16" or 1ft 3-1/32" or 1/64" etc. then you are exploding the brain of semi-skilled contruction workers. Paper roll commercial is sized to A-0(841x1189mm) but can be plotted into smaller paper size drawings ( A-3, A-2 A-1) depend on your plot-setting in plotter dialog box (model drawing). In paper space drawing you need to insert your desired standard template frame size.