AutoCAD has both automatic and associative dimensioning, the terms meaning:

AutoCAD allows different 'types' of dimensions to be added to drawings. These are displayed in Figure 14.1 and can be categorised as:

1. Linear: horizontal, vertical and aligned

2. Baseline and Continue

3. Ordinate: both X-datum and Y-datum

4. Angular

5. Radial: diameter and radius

6. Leader: taking the dimension text 'outside' the object.

Figure 14.1: The AutoCAD dimension 'types'.

All dimensions used with AutoCAD objects have a terminology associated with them and it is important that the user has an understanding of this terminology.

The dimension terms used in AutoCAD, displayed in Figure 14.2, are:

1. The dimension and extension lines
   These two features consist of:

   1. the dimension line

      • the actual line

      • the dimension text arrowheads

      • extension lines

   2. the extension line

      • an origin offset from the object

      • an extension beyond the line

      • spacing (for baseline)

2. Centre marking
   Circular features can be displayed with either a mark, a line or nothing.

3. Dimension text
   It is possible for the dimension text to:

   1. have interior dimension line drawn or not drawn

   2. display alternative units (i.e. imperial)

   3. have a frame drawn around it.

4. Arrowheads
   A selection of available arrowheads is displayed.

5. Dimension text alignment
   The dimension...