When you label an object, the program uses the current Object Label Settings to add a label to the object. In the case of a line, you can add both a distance and a direction label. For an arc, you can add all the curve labels like delta angle, arc length, chord length, tangent, etc.
Labeled objects adhere to a set of rules designed to help keep your drawing labels consistent. For more information on these rules see Labeling Drawing Objects.
Toolbar: 
Labeling Drawing Objects
Label Settings
Working with Drawing Objects
Selecting Objects
Editing Drawing Objects
Hiding Drawing Objects
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