Light Transport; Low Wing; 2 Turbojet Eng
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Communication Breakdown; Confusion
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Flight Crew Became Reoriented
Airport; Chart Or Publication; Human Factors
Cleared; 'F; H; hold short of RWY 4R'. Once on H realized there is no hold short line in front of us ergo we are on the runway even though not passed the runway edge markings. I was slowing to stop to clarify with Ground; frequency was packed with voices. PIC said 'clear this runway' so I went across and held on C behind another aircraft. About 60 seconds later Ground said 'you went further than you were supposed to go but its ok.' Even though the RWY was NOTAMed out of service we both had that sinking feeling maybe the NOTAM was misread and we're on an active runway. No air traffic approaching. No ground conflict. We should have held on F short of H where there is a hold short line. But instructions were F; H hold short of 4R. Technically we are on the runway after we pass the hold short line on F.
First Officer reported flight crew failed to follow ATC instructions and entered Runway 4R when  instructed to hold short.