Thedialog box enables you to control the precision displayed by 2D measurement markups for each 2D sheet in the DWF file. Measurements can be in Imperial (feet and inches) or metric units.
In Design Review, the units and scale from the original drawing are used by default. However, if the original drawing did not specify units of measurement, only numeric values of the measurement are displayed in the resulting DWF file. You may set the units and scale for all measurements yourself either before or after a measurement markup has been created for each 2D sheet in a DWF file.
A drawing has both drawing units and display units. Drawing units are the intended units of measurement of the real-world object. Because a 10-foot by 10-foot room cannot be represented on screen at its full size, each unit in a drawing represents its real-world unit, such as a foot in this case. (If you select inches, it displays 10 inches by 10 inches. If you select centimeters, it displays 10 cm by 10 cm. If you select feet, it displays 10 feet by 10 feet.) If the drawing units are unknown, the measurements display as “10 by 10”.
Display units are the units displayed in the measurement markups. Unless you change the display units, the display units match the drawing units. A 10-foot by 10-foot room is displayed as 10 feet by 10 feet, but it can also be displayed as 120 inches by 120 inches, 3.048 m by 3.048 m, 304.8 cm by 304.8 cm, and so on. Display units cannot be applied until the drawing units are known.
If a scale was set when the DWF file was published, that scale is reflected in the measurements displayed in Design Review. A 1-to-1 scale is displayed for the open drawing. It shows 1" = 1" (1 inch equals 1 inch) for Feet and Inches or 1:1 for metric scale, depending on whether the drawing was set in Imperial (feet and inches) or metric.
If the published scale is incorrect or you prefer a different scale, you can change the published scale for the 2D sheet.
Custom Scale enables you to enter a custom scale using the On Page and Actual options. For example, a 1" = 10' (1 inch equals 10 feet) custom scale designates that each inch displayed in the drawing represents 10 feet in the real world.