You may cord & plug fixtures; male cap to single recept (twistlock), cord is usually a factory option. You may also use any suitable wiring method from Art 300, excluding using 'cord' for permanent wiring (ie: into a 'j' box..
Some mfg have a 'plug-n-go' system; various lengths of cable with modular plugs; multi-circuit; multi-level lighting, etc.
Check 'www.ruudlighting.com' for some info on hi-bay/low bays.
Also, keep in mind that IF the area you are installing HID's in requires emergency lighting, you may require quartz restrike option in some oh the low/hi bays.
Uses on cord is Art 400, wiring methods is Art 300; Lighting is`within Art 410