### 3.3 Definitions

Definitions give names to `sketch` objects. Definitions alone are benign. A `sketch` input file consisting entirely of definitions will generate no drawing. Only when definitions are referenced do they potentially lead to ink on the drawing.

The intent of definitions is to make `sketch` code more concise and readable. There is no input file employing definitions that could not be re-written without them.

Definable objects include any result of an affine arithmetic expression (scalar, point, vector, or transform), any drawable object (dots, line, curve, polygon, block, sweep, put, repeat, or special), and option strings. In addition, tag definitions, which have no associated object at all, allow the meaning of other definitions to be selected from a set of alternatives. Since tags may be defined (and undefined) in the command line of `sketch`, they can be an aid in the script-driven preparation of documents.