I have experimented with the open source jbig2enc library available at http://github.com/agl/jbig2enc, which has a encoding parameter called the “threshold”, described like this:
“sets the fraction of pixels which have to match in order for two symbols to be classed the same. This isn't strictly true, as there are other tests as well, but increasing this will generally increase the number of symbol classes”
The included command tool accepts values for this parameter between 0.4 and 0.9, with 0.85 as the default.
I have found replaced digits in single-page numerical tables encoded with this parameter set as high as 0.82. As with the other examples you have found, the errors are not in any ways obvious to the eye which is, of course, the real problem.
Since JBIG2 has been supported in PDF since 2001, it would be surprising if only Xerox have fallen into this trap.
Yeah they serve all right.. I'm guessing it's not too terribly dangerous to fly about in an armored helicopter shooting at a bunch of asiatic hillbillies with AK-47s.
With AK-47s, and heavy machine guns, and RPG launchers, and portable surface-to-air missiles and such. Oh, and there's always the risks of bad weather and mechanical failure inherent to helicopter flight. Helicopters are dangerous, period, and the Apaches are far from invulnerable. A number have been lost in Afghanistan and Iraq, and some crews have died.
In general, when a piece of military hardware is heavily protected, it also faces powerful threats that make that protection necessary. Otherwise it'd just be carrying extra dead weight that would better be replaced with useful equipment. The military isn't in the business of building invulnerable weapons or letting soldiers fight in "god mode".
And don't you think their opponents wouldn't love to have the coup of bringing down a royal? Just by being in the combat zone, they put themselves at risk.
Because you know if there's ever an imminent threat the members of the Royal Family aren't going to be sat at Buck House with a cuppa tea counting down the seconds...they'll be on their merry way to the other three corners of the globe.
Any member of the Royal Family who did that would rightly be disowned by the rest of the family and the British public, and would probably be looked down upon by much of the rest of the world as well. If the monarch herself did it (and I can't imagine Elizabeth II doing it in a thousand years--she may look like a little granny, but she has far too much backbone for that), she would effectively have abdicated. In the face of such a selfish, craven act, Britain would either find itself a new monarch with more spine, or get rid of the monarchy entirely.
The Royal Family enjoys a lot of privileges, but in the end they exist to serve the British state, as its personification. Their lives are far more controlled and circumscribed than ordinary people.
Just look at the case of Edward VIII to see how Britain might treat a monarch who doesn't take his duty seriously.
To me, the dividing line between a minicomputer and a microcomputer is the capability for virtual memory. Desktop computers have been architecturally minis since the 68030 and i386.
That's kind of funny to me, since the term "minicomputer" came into vogue in the later 1960s to describe computers like the original PDP-8 (the "Straight 8"). Far from being a virtual memory machine, the PDP-8 was a 12-bit architecture with a minimal instruction set and a very limited address space. Later PDP-8s used bank-switching to expand their addressable memory, as did the later 16-bit PDP-11. In many ways the early minis were architecturally similar to 8-bit and 16-bit microcomputers. Compared to them, the 80386 and 68030 look like ultra-powerful monsters.
Stupidity, like virtue, is its own reward.