Dimensioning with AutoCAD - Section 6

27.2 Types of dimensions

All dimensions available in Autocad are organized in the Annotate tab, in the Dimensions section.

27.2.1 Linear Dimensions

Linear dimensions are the most common and show the vertical or horizontal distance of two points. To create it, we simply indicate the two necessary points and the location that will have the dimension, which establishes if it is horizontal or vertical, as well as the height of the reference line.
When activating the command, Autocad asks us for the origin of the first line, or, by pressing "ENTER", we designate the object to be dimensioned. Once this is defined, we can set the height of the reference line with the mouse or use any of the command window options. The ANGLE option rotates the dimension text by the specified angle, and the Rotate option gives the extension lines an angle, though that changes the value of the dimension.

If we want to modify the text of the dimension, or add something to the value that is presented automatically, we can use the textM or Text options; in the first case the window for the multiple text editing that we saw in section 8.4 opens. In the second case we simply see the text edit box. In this case it is even possible to delete the value of the dimension and write any other number.

27.2.2 Aligned Dimensions

Aligned dimensions are created exactly like the linear dimensions: you have to indicate the start and end points of the reference lines and the height of the dimension, but they are parallel to the contour of the object to be bound. If the segment to be bound is neither vertical nor horizontal then the resulting value of the dimension is different from that of the linear dimension.
This type of dimension is very useful because it reflects the actual measurement of the object and not that of its horizontal or vertical projection.

27.2.3 Baseline dimensions

The baseline coordinates generate different dimensions that have their starting point in common. To create them there must exist an existing linear dimension like the one we saw in the before. If we use this command immediately after creating a linear dimension, then Autocad will take the linear dimension as the baseline. If, however, we have used other commands, then the command will ask us to designate the dimension.