DWG DXF Units Alert Box

	Product:	MicroStation
	Version:	V8 2004, XM, V8i, CONNECT
	Environment:	N\A
	Area:	DWG
	Subarea:	General

Overview

In MicroStation V8 it is important to correctly specify the units for a file. Many of MicroStation's tools, such as dimensioning, placing cells and reference files, rely on the file units to work correctly. Unfortunately in many AutoCAD files it is not possible for MicroStation to accurately infer the file units.

There are essentially two types of linear units used in AutoCAD as specified by the AutoCAD "LUNITS" variable. Files with Engineering and Architectural (LUNITS =3 & 4) are implicitly English units, feet and inches, so there units are known. The other types, Scientific, Decimal and Fractional (LUNITs = 1, 2 and 5 respectively) do not imply a specific unit of measurement.

A second value (INSUNITS) was introduced in AutoCAD 2000 to further specify units and allow for the type of automatic scaling that MicroStation V8 performs when "True Scaling" is specified. Unfortunately the Design Center Units variable (INSUNITS) does not exist in pre-AutoCAD 2000 files and is inconsistently set in many AutoCAD 2000+ files. MicroStation V8 allows the user to either use the Design Center Units specification or to specify units explicitly.

Alert Box for Unknown Units

An alert box is automatically displayed when a file is opened and the units are not known. There are three circumstances where the dialog will appear.

The file is either Decimal, Fractional or Scientific and units other than Design Center have been selected. This would be the most common occurrence. It the units displayed are correct than you can simply hit OK. If you know that the units are correct for all files of this type, select the "Do Not Display" toggle to avoid seeing this alert box again.
Design center units have been selected, but are not available or unspecified in the selected file.
The file is of type Architectural or Engineering and the units other than inches have been selected. This would only occur if the user explicitly changes the unit setting for Architectural and Engineering files to something other than inches.