What AN-6 means, why the number is not the hose bore, the 9/16 x 18 thread and 37 degree flare, PTFE versus rubber hose, metric adaptors, and how to specify a line.
How to identify the brake line fitting you need: thread sizes and pitches, male and female, fixed and swivel, circlip groove fittings, banjo bolts, flare types and bulkhead fittings.