Use "link-layer header type" as the term for DLT_ values; it doesn't
necessarily correspond to the actual data link type of the device
(802.11 devices, for example, can supply Ethernet headers).
pcap-linktype man pages; it should be section 7 for UN*Xes using the
V7/BSD conventions (this includes *BSD, Linux, and Mac OS X), and
section 5 for UN*Xes using the System V conventions (this includes
Solaris and HP-UX, and possibly AIX).