PCI devices

Vendors

The top level of hierarchy is a vendor list. Each vendor has a 2-byte long id, stored in database as 4 hexadecimal digits (with lowercase letters). They can be browsed here.

Devices

Each vendor contains a list of its devices. Each device in the list has a 2-byte long id, stored the same way as vendor id (4 hexadecimal letters).

Subsystems

A device can consist of more sub-systems. Each sub-system has 4-byte long id, stored as 8 hexadecimal letters, split in the middle by a space (for example 1234 abcd could be a sub-system id). The first quad of digits is considered a vendor id (from the same list of vendors). The vendor of the sub-system can be different than vendor of the device.

See also

You can have a look at PCI device classes.