BricsCAD Unit Settings

Quick answer: UNITS (via the Settings dialog) and -UNITS (via the Command line) set your drawing’s base linear and angular units. INSUNITS defines what one drawing unit actually equals, and separately, PROPUNITS lets individual length, area, and volume properties display in whatever unit fits best, independent of the drawing’s base unit.

Setting Units: UNITS vs -UNITS

UNITS: opens the Settings dialog to set linear and angular units.
-UNITS: does the same thing, but entirely from the Command line.

The Base Unit: INSUNITS

INSUNITS defines what one Drawing Unit (DU) actually equals, and is used for automatic scaling when you insert blocks or attach Xrefs. It also serves as the base unit for any unit conversions elsewhere in the drawing. If INSUNITS is 0 (undefined), the PROPUNITS mechanism below is disabled entirely, since there’s no base unit to convert from.

Displaying Properties in Different Units

Any length, area, or volume property can be shown in whichever unit you prefer, separately from the drawing’s base unit, controlled by PROPUNITS.

A couple of specific behaviours worth knowing:

If LUNITS is set to 3 (Engineering) or 4 (Architectural), property values are formatted using imperial notation.
With bitcode 1 of PROPUNITS (“Format length properties”) set, typing a unit directly into a length field auto-converts it to the drawing’s base unit. For example, with INSUNITS set to mm, typing 2m into a length field converts it to 2000.0000 mm, and typing 1ft converts to 304.8000 mm.

Unit System Variables

Variable	Controls
`INSUNITS`	The value of 1 Drawing Unit, used for scaling on insert/attach. When both `INSUNITS` and `PROPUNITS` are on, Length, Area, Volume, and Inertia properties get formatted with their own dedicated units
`MEASUREMENT`	Imperial or Metric drawing units; also controls whether ANSI or ISO hatch pattern and linetype files are used
`PROPUNITS`	Which property values auto-format with a dedicated unit when `INSUNITS` isn’t zero, stored as a bitcode (the sum of whichever options are selected)
`LUNITS`	The linear unit type: Scientific, Decimal, Engineering, Architectural, or Fractional
`LUPREC`	Decimal places shown for linear units
`AREAPREC`	Decimal places shown for areas, when the Area bit of `PROPUNITS` is on; a negative value falls back to `LUPREC`
`VOLUMEPREC`	Decimal places shown for volumes, when the Volume bit of `PROPUNITS` is on; a negative value falls back to `LUPREC`
`LENGTHUNITS`	Which units are used for displaying lengths, when the Length bit of `PROPUNITS` is on. Empty means lengths show in the drawing’s base unit (`INSUNITS`); with several selected, whichever fits best is used
`AREAUNITS`	The same idea, but for areas
`VOLUMEUNITS`	The same idea, but for volumes
`UNITMODE`	How Imperial units are displayed

Note: Octave’s own documentation describes both AREAUNITS and VOLUMEUNITS using wording copied from the LENGTHUNITS row (“all lengths are displayed…”), which looks like a copy-paste artifact rather than an intentional statement. The table above reflects what each variable is actually named and scoped to do, areas for AREAUNITS, volumes for VOLUMEUNITS, rather than repeating that inconsistency.

Entering Angles

AUNITS sets the angular unit type, and ANGDIR sets which direction counts as positive: counterclockwise by default, or clockwise. Angles are measured relative to the positive X-axis of the current coordinate system.

You can type angles in five different formats:

Format	Example	AUNITS value
Decimal degrees	`37.456`	0
Degrees/Minutes/Seconds	`37°27'22"` or `37d27'22"`	1
Gradians	`41.6178g`	2
Radians	`0.6537r`	3
Surveyor’s Units	`N52°32'38"E` or `N52d32'38"E`	4

Surveyor’s Units are measured from North or South, toward East or West.

Frequently Asked Questions

What’s the difference between a drawing’s base unit and its property display units? INSUNITS sets the base unit the whole drawing scales against. PROPUNITS, along with LENGTHUNITS, AREAUNITS, and VOLUMEUNITS, lets individual properties display in a different, more convenient unit without changing that base.

Why would typing “2m” into a length field give me a value in millimetres? Because bitcode 1 of PROPUNITS auto-converts whatever unit you type into the drawing’s base unit, set by INSUNITS. If the base unit is millimetres, that’s what you’ll see.

What are Surveyor’s Units, and how are they measured? A way to enter angles relative to compass directions, like N52°32'38"E, measured from North or South toward East or West, rather than as a plain number of degrees.

Does MEASUREMENT only affect whether units show as Imperial or Metric? No, it also determines whether BricsCAD uses ANSI or ISO hatch pattern and linetype files.