To add a new representation rule for a layer in ArcMap that already has a representation, double-click the layer (in this example, BuildingP_Rep) in the ArcMap table of contents to open the Layer Properties dialog box.

Click the Create New Rule button to add a new representation rule to the feature class representation.

Click the Layer Options button and point to Units. Choose Points as the unit of measurement for the symbols.

Click the name of the new rule to select it, then type a new name to rename it.

The new representation rule in this example consists of a single marker symbol layer with a default representation marker (an 8-pt black square). You'll see how to change this to a 2-pt red square.

Inside the marker symbol layer, click the black square representation marker. On the Representation Marker Selector dialog box, click Properties. The Marker Editor opens with the black representation marker filling the canvas.

Use the Select Part tool to select the representation marker. A representation marker is made up of symbol layers and geometric effects just as representation rules are. This representation marker consists of a single fill symbol layer, filling the square with solid black.

Click the swatch next to the Color property in the fill symbol layer and choose a red from the palette that opens. Click OK to close the Marker Editor, then click OK to close the Representation Marker Selector dialog box.

Click the Size property text box. Type “2” and press Enter. The New Buildings representation rule is now symbolized with a marker symbol layer containing a 2-pt red square.

Click OK. A Warning dialog box appears. This warning is to let you know that the changes you are making to a rule will be stored in your database.

Click OK and view the results. Notice that the points are still symbolized with the default symbol. They are symbolized this way because their values in the RuleID field are all set to 1.