Compaq 1610 Reference Manual page 112

Part 15 of the Federal Communications Commission (FCC) Rules
and Regulations has established Radio Frequency (RF) emission
limits to provide an interference-free radio frequency spectrum.
Many electronic devices, including computers, generate RF
energy incidental to their intended function and are, therefore,
covered by these rules. These rules place computers and related
peripheral devices into two classes, A and B, depending upon
their intended installation. Class A devices are those that may
reasonably be expected to be installed in a business or
commercial environment. Class B devices are those that may
reasonably be expected to be installed in a residential
environment (i.e., personal computers). The FCC requires devices
in both classes to bear a label indicating the interference potential
of the device as well as additional operating instructions for the
user.
The rating label on the device shows which class (A or B) the
equipment falls into. Class B devices have an FCC ID on the
label. Class A devices do not have an FCC ID on the label. Once
the class of the device is determined, refer to the following
corresponding statement.