A generic symbol defines a family of similar symbols; it contains all entities pertaining to this family. You can arrange geometry and text in the generic symbol in groups and subgroups, creating a tree structure of symbol definition.

The tree definition structure helps you create symbol instances. When you specify the groups to include, the system assembles an instance out of predefined blocks, or groups. A group can consist of other subgroups and independent entities. The system always selects these independent entities on each level when you select the group to which they belong. Subgroups of different subgroups can share the same name.

Each level of symbol definition, containing more than one group, is characterized by the group attribute restricting the selection of groups at the specified level. That is, you can choose Exclusive from the GROUP ATTR menu to define groups, so that you include only one of them in the symbol instance, or you can use the Independent command to define them, so that you can select any number of groups (or none).