You might want to link several groups together so that you can share descriptions or simplify each part of a description. For example, the description of the ARM Evaluator-7T provided in Eval7T.bcd is split into a description of the board, *BOARD=Evaluator7T, and a description of the processor on the board, KS32C50100 or S3C4510B depending on the version of the board. This is shown in Figure 4.4.

Figure 4.4. Board and chip groups for the Evaluator-7T

This is shown in tree form in Figure 4.5.

Groups can contain BoardChip_name references to other groups, so that you can build multi-layered descriptions. For example, if you are building a simple Ethernet router, you might use the network interface on the KS32C50100 with a second network interface provided by an AMD LANCE. This configuration is shown in Figure 4.6.

Figure 4.6. Board and chip groups for the EtherRouter board

This is shown in tree form in Figure 4.7.