More on Numbers

Earlier I discussed Numbers in a general post about improving PDF for easier parsing.

I have two more notes to add on the subject of numbers.

"." is not a number

PDF ISO-32000-1:2008 states that:

A real value shall be written as one or more decimal digits with an optional sign and a leading, trailing, or embedded PERIOD (2Eh) (decimal point).

Adobe Acrobat Reader 9 clearly ignores this and accepts a single period as zero. This example (7-3-3-t01-fail-b.pdf) from our PDF 1.4 test set clearly shows that the colors red (on the RGB page) and black (on the CMYK page) were parsed with no problem.

1 0 . rg 72 72 72 72 re f

0 1 0 rg 72 216 72 72 re f

0 0 1 rg 72 360 72 72 re f

..

0 1 1 rg 72 72 72 72 re f

1 0 1 rg 72 216 72 72 re f

1 1 0 rg 72 360 72 72 re f

. 0 0 rg 72 504 72 72 re f

Numbers in PDF/D

In addition to earlier notes on parsing numbers, the above behavior will be considered an error in PDF/D. 

Also, in our 10,000's of test files we have often seen number arguments terminated in content streams by the operator like this:

... 2 0 0 2 0 0cm ...

Acrobat does not tolerate this but we have seen other PDF software (including our own) look past this error. PDF/D will require delimiters or whitespace to terminate number tokens.