The values of an attribute can be thought of as a table with one row for each of its values, as seen in Table 7-3. Each row in the table selects one or several geometric entities. Each of the PCB component and PCB pad attributes can have associated fields. See PCB Component Attributes for more information about fields. Each value within an attribute must be unique, while the fields need not. The values and fields are strings.

The operations Array, Copy, Move, and Rotate can create index attributes by assigning 1-based values to the output objects. The values correspond to the object’s array index.

You can use a Logical Expression Selection (Geometry Sequences) or a Logical Expression feature to quickly select some of the output objects or entities using Boolean expressions. For example, the expression

selects one of the points in the array of points shown in Figure 7-16.

The PCB component attributes can be created when importing PCB files. The PCB component attribute has two fields: package and value. Setting up a table for this attribute will result in three columns: the attribute values and the fields package and value, as seen in the example in Table 7-4.

For the example in the table above, a Logical Expression Selection feature with the expression imp1.component.package('R_0805_4') will select the same entities as the expression imp1.component('C1', 'R2').

In the same way, importing pads will result in a pad attribute with the fields component, pin, net, package, and value, as seen in the example in Table 7-5.

For the example of the table above, a Logical Expression Selection feature with the expression imp1.pad.net('GND') will select the entities of C1/2, C2/2, and R1/2.