The board games Imperium (the Interstellar Wars era itself) and Dark Nebula (Terrans vs Aslan) are both considered canon  for the OTU and both describe historical periods during which  empty hex jumps were not possible.
		
		
	 
In the board game 
FFW ships expend all their jump fuel regardless of the distance they jump.  Thus, according to the canonical 
FFW board game, jump fuel regulators do not exist until after the Fifth Frontier War.
Does what I wrote above sounds in any way plausible to you?
Or does what I wrote suggest that the many design feature of 
Traveller's many board games have different levels of canonicity?
	
	
		
		
			In order to preserve this canon history the designers at SJG had to preclude empty hex jumps.
		
		
	 
I was part of the play test and, no, they didn't.
The jump lines found in 
Imperium and 
Dark Nebula were roped in as an excuse to explain away certain aspects of canonical history.  There was no pressing concern about maintaining anything from either game, but there was a desire to maintain information from 
Rim of Fire.  If the games actually were important, the "Imperium" would have been reduced to "seventy stars centered on Capella" and tankers would be able to refine fuel directly from stellar atmospheres because both statements are part of the 
Imperium board game.
The prohibition on empty hex jumps has it's origins in the canonical conduct of the various wars; specifically the astrography of the region around Sol and the question of why the Ziru Sirka had seemingly not directly attacked Earth across the "Sirius Gap".  However, the part of the question dealing with Sirius attack had only become prominent with the release of SJG's 
Rim of Fire.
GDW's own description of the wars had never mentioned such an attack, but those descriptions mentioned little in the way of actual attacks and battles.  
GDW's work on the wars was both deliberately and artfully vague so the actions in several wars across hundreds of years had been laid out in just a few paragraphs scattered about in publications like 
Argon Gambit and 
AM:Solomani.
SJG's own 
Rim of Fire greatly expanded on the descriptions of the wars.  Sadly, 
RoF's author chose to use the 
Imperium map rather than the normal 
Traveller map of the same region when creating his far more detailed history.  That was probably due to time constraints, he was writing a sourcebook for an entire sector after all and he couldn't afford the time to play out a dozen or so 
TCS/FFW-lite map exercises to craft a history which would still include the few 
GDW facts.  The result of his time constraints and choices however was that the 
ISWauthors now had to explain detailed canonical information 
which SJG alone had created along with the far limited canonical information from 
GDW.
The 
ISW authors also were under great time restraints and other pressures.  They were writing a setting which was meant to be as self-contained as possible, a setting using rules from a RPG system, 
GURPS 4e, which wasn't even fully released yet, a setting which needed it's own space combat and trading rules, and a setting plunked smack dab into a period of 
Traveller history which still had huge "holes' in it.  They had to pick and choose where to expend their efforts.
Considering what they had to do and what they accomplished, the 
ISW authors succeeded fantastically.  What they created wasn't perfect however.
And the 
ISW authors did not fail.  Instead, the 
ISW playtesters 
failed the 
ISW authors.
I was part of the playtest and, when jump lines were brought up, quickly pointed out the troubling canonical implications of their use.  Sadly, the thread discussing jump lines and, by extension the Sirius Gap question, became bogged down in the usual nonsense by the usual suspects regarding mass requirements for jump exits.  Jump masking and jump shadows got roped in too and before long the thread was an unmanageable mess.  Every time a new thread meant to discuss jump lines was begun, the same old assclowns shitted it up with the same old arguments.
(FWIW, I suggested a "soft' explanation for the Siruis Gap question relying on an inability to perform "squadron synch" jumps in and/or out of empty hexes.  This soft explanation would keep 
fleets from crossing the Sirius Gap, this preserving the 
RoF information, while not preventing PCs from crossing the same.)
I have no doubt that the 
ISW authors at first skimmed the threads in question, only to correctly dismiss the first thread and the follow-ups as a waste of their very limited time.  They roped in 
Imperium to solve what was to them a minor problem and went on to more pressing matters.
In the end, 
ISW messed up with it's adherence to jump lines.  An adherence which had  more to do with maintaining continuity with 
RoF, questions about the Siruis Gap, and 
failure by the playtesters than anything else. 
	
	
		
		
			In fact it is in the technology development rules of the Dark Nebula game that empty hex jumps become a possibility.
		
		
	 
That's an optional rule.  
Dark Nebula also has it's map layout change with every playing.  If everything about 
Traveller wargames is canonical, the stars themselves routinely shift about in the Dark Nebula Sector.  There's an honest-to-ghu nebula on the 
DN map also.  Care to point out that nebula on the Dark Nebula Sector map?
It's in the wargame so it simply 
must be there, right?  
