In a PCB, each component is identified by a reference consisting of a code and a progressive number. The prefix (R, C, U etc.) specifies the type of component while the progressive number (R1, R2 etc.) identifies each individual component. The operation of assigning a reference to the components can be either manual or automatic.


Each reference must be unique within a project.

Manual annotation

The manual annotation of components can be done by opening the device properties window and typing the reference directly. This is an operation suitable for projects of low complexity or when you want to assign a precise reference to certain components.

Automatic annotation

Automatic component annotation assigns a single reference to all components of the PCB. You can only annotate some components that do not have a valid reference (references with ?).

To activate automatic annotation

  1. Choose the PCB » Annotate command or click on the tool in the toolbar.

  2. The PCB Annotation dialog box opens.

  3. Set the parameters of the dialog box and click on Ok.

See also