It is page 650 in the (normative) Annex C = Implementation Limits for PDF readers and writers:

Additionally, = conforming writers should adhere to the following constraints, and = conforming readers should accommodate PDF files that obey the = constraints.

The = minimum page size should be 3 by 3 units in default user space; the = maximum should be 14,400 by 14,400 units. In versions of PDF earlier = than 1.6, the size of the default user space unit was fixed at = 1=E2=81=8472 inch, yielding a minimum of = approximately 0.04 by 0.04 inch and a maximum of 200 by 200 inches. = Beginning with PDF 1.6, the size of the unit may be set on a = page-by-page basis; the default remains at 1/ 72 = inch.

In= other words: you need to change the unit per page so the page is at = least 3x3 and maximally 14400x14400.

On 9 Jul 2020, at 12:10, Hans Hagen <j.hagen@xs4all.nl> = wrote:

On 7/9/2020 9:08 AM, Taco Hoekwater wrote:
On 9 Jul 2020, at 08:32, Hans Hagen <j.hagen@xs4all.nl> = wrote:

On 7/8/2020 8:14 PM, Gerben Wierda = wrote:
I found out = this in the PDF spec:
The minimum page size should be 3 by = 3 units in default user space; the

I never noticed that ... what section/paragraph in the = spec?
It=E2=80=99s in the implementation = limits for Acrobat, not in the normative section.

Great. That used to be 1 bp so = now it's more. As it happens, we do have a check for this in context so = we can adapt it ... but, as this 3 bp is kind of arbitrary and because 3 = bp becomes a float and thereby ends up slightly less than the integer 3 = we can best play safe and revert to the usual tex joke, so i now set the = minumum to

= \luaexpr{math.pi}\onebasepoint

which = then gives:

/MediaBox [ 0 0 = 3.141539539 3.141539539 ] because after all, any rediculous minimum will = do and that way a user can still figure out that it's a value set by = context.

Hans

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