You can use the Units dialog choose the display and input format of length and angle measurements. The command location has moved around a bit in recent years: In LT 2010, it's under the Application Menu-->Drawing Utilities-->Units; in LT 2009, it's on the Tools tab, Drawing Utilities panel; in previous versions look under Format-->Units; and in all versions you can type UNITS.
For length, you have the following options. The numbers in parentheses show how a sample length -- 41.5 units -- would be displayed with each type.
- Architectural (3'-5 1/2")
- Decimal (41.5)
- Engineering (3'-5.5")
- Fractional (41 1/2)
- Scientific (4.15E+01)
You can choose the precision you want to display, from low to high -- this doesn't affect input, just how many decimal places or fraction denominators you'll see when you list something or use a measuring command.
You can also choose the format of your angles. The numbers in parentheses show a sample angle -- 30.5 -- would be displayed for each type.
- Decimal Degrees (30.5)
- Degrees/Minutes/Seconds (30d30'0")
- Grads (33.889g)
- Radians (0.5323r)
- Surveyor's Units (N 59d30'0" E)
You can set the display precision for angles too, and choose to have them go clockwise instead of counterclockwise.
For any of these linear or angular formats, you can only use special characters that correspond to the current type. For instance, entering 4'6 when your type is set to Decimal or 45d10 when your type is set to Grads won't work. But decimal entry always works.
The Insertion Scale option has to do with copying content between files that have different units. It's related to other settings in the Options dialog, so I think I'll say more on that another day.
Finally, down at the bottom, is the Direction Control dialog.
This enables you to set the "zero" angle for your file -- to the right (East), up (North), left (West), down (South), or any direction you choose. (East is the default -- it corresponds to most standard coordinate systems.)