Each document in the software is a container of sheets, where each sheet is a virtual sheet of paper that displays model information.
The software supports measurements in two different spaces: paper space and model space. The paper space units represent physical measurements on the virtual sheet. The model space units represent real-world measurements associated with the model.
Within the drawing environment, "model space" is synonymous with the term "world space".
You can define the relationship between paper space and model space on the Sheet Setup dialog box. The default relationship between the paper and model spaces is 1:1. In other words, one unit of model space is equivalent to one unit of paper space. For example, if a text box with a font size of 1 inch in paper space is compared to a vertical line 1 inch in length, the text box and line appear on the paper to have the same height. However, if you change the drawing scale to 1:2, the line appears half as tall on the sheet as the text. If you change the drawing scale to 2:1, the line appears twice as tall on the sheet as the text. In either case, if you select the line, the length readout remains at 1 inch.
In the current software, you can place only balloons, leaders, and dimensions in paper space. These graphics annotate objects in the model space but appear in paper space. You can place text boxes in either paper space or model space.
If you insert an .igr or .sym document into the drawing sheet with Insert > Object, the terminators, spaces, text, and styles appear in paper units relative to the source document. The dimension lines and extension lines scale as though they are in real-world units. This behavior can cause the dimensions and text to appear very large or small in the container document. You can set or change the size for dimension text and annotations by clicking Style on the Format menu. On the Style dialog box, you select the type of style you want to set or modify (dimension or text), and then click New or Modify to set the font size for dimension text or a text box. Changing the font size of dimension-text style or a text-box style changes only the dimension text or annotations with the modified style applied to them.
You can also set the font size for individual dimension text or annotations by overriding the style that you applied. You do this by selecting the dimension or text box and editing its properties with Properties on the shortcut menu or from the Edit menu.
You can adjust how the model units fit within the printable sheet area by clicking Sheet Setup on the File menu. On the Size and Scale tab, you can select a scale setting by clicking an item on the Select Scale dropdown list. The value that you select causes the model to resize within the printable area, but neither the paper unit information (dimensions and annotations) nor model unit information is scaled.