@kasperd @soatok @geoffl @publius @aires @matildalove I am not saying this.
Interpretations and implementations of a standard can differ which may lead to interoperability problems.
Example:
"Both versions of the ISO 32000 standard define the border array using the following sentence:
“The array consists of three numbers defining the horizontal corner radius, the vertical corner radius, and border width, all in default user space units.” (ISO, 2008, ISO, 2008, p. 384; ISO, 2017, ISO, 2017, p. 465)
Accordingly, the interpretation of the standards used in PDFBox agrees with the standard; border width can be specified with a floating point number. However, the Adobe reader software expects an integer, and ignores non-integer values, such as 3.0, by treating them as having a value of zero."
(...)
"
A contributor reports in PDFBOX-3983 that Acrobat Reader fails to display some outlines and borders where the miter limit is set to a value of zero or less. The miter limit indicates how junctions between lines should be drawn. The ISO 32000-1:2008 standard states:
Parameters that are numeric values, such as the current colour, line width, and miter limit, shall be forced into valid range, if necessary. (ISO, 2008, p124)
The statement was revised in ISO 32000-2:2017 by the replacement of “forced” with “clipped” (ISO, 2017, p. 157).
Accordingly, one interpretation might be that a compliant PDF reader would be able to display a document correctly regardless of the value of the miter limit recorded because it would automatically correct the value. However, Adobe implementations appear not to correct the value."
https://www.sciencedirect.com/science/article/pii/S0164121219302262#bib0069