For a sector at the cutting edge of technology, aviation has a fairly crude annual measure by which performance is judged.
Every years, manufacturers and others in the industry, as well as us in the media, obsess over the order numbers that Boeing and Airbus post at the Farnborough or Paris air show.
When the figures have been totted up, there emerges a hyperbolic consensus that either Airbus or Boeing has "won" the air show.
Of course, neither Airbus nor Boeing – regardless of an air-show win or loss – stand to lose or gain enough market share for their duopoly to be threatened. For now, at least.
Boeing by all accounts "won" the 2017 Paris air show – but it is hard to recall, without archive-trawling, who has been victorious at Le Bourget in previous years. The fame is fleeting.
Still, there is of course value in the marketing and media exposure that a big air show's global audience generates for manufacturers, their products and, indeed, their customers.
The 2017 edition of the Paris air show bucked the pre-event received wisdom that high order numbers from airlines and lessors were unlikely.
Indeed, commitments announced during the show totalled over 1,200, with 175 more jets covered by options/purchase rights.
For Boeing, many of these announcements involved lessors and airlines signing up for its new narrowbody variant, the Boeing 737 Max 10, which was launched at the show.
The headline figure can be viewed as a sign of success, on its own terms.
But the business of selling aircraft naturally necessitates actually delivering them.
Of the over 1,200 commitments announced at Paris, only 350 deals were firm orders. Another 229 were conversions of existing orders, predominantly from the 737 Max 8 to the larger Max 10.
Among financiers, some viewed the figures with a degree of suspicion.
"Great to see the manufacturers in full swing on the orders at the air show... The aircraft equivalent of 'My dad's bigger than your dad' is hilarious," one source told FlightGlobal.
"'I'm delighted to announce an order for a huge number of planes to be delivered in the future at some point for an airline that has yet not signed a proper contract, paid any deposit or got the order actually approved by its board.' Explain to me how that is really an order? Is that the reverse of: 'If it looks like a duck, waddles like a duck and quacks like a duck, then it's a duck?'," quips the source.
That may strike some as overly cynical.
However, it is worth remembering that at Farnborough 2016, Virgin Atlantic stated that its fresh order for Airbus A350-1000s was not replacing a dormant order for A380s placed 15 years earlier.
The airline was originally meant to start taking delivery of the A380 over a decade ago. There are few who expect the airline ever to take those A380s now; even its chief executive Craig Kreeger has said the chances of the double-decker type entering Virgin Atlantic's fleet are remote.
So, announced deals do not automatically translate to deliveries. And if you want to judge how Boeing and Airbus are performing, the crucial metric remains the number of aircraft being handed over – a figure free of any smoke and mirrors used to add to an air show's drama.