PageLabel Num Trees not starting with 0

[asciim0]

Quick question about what is in scope for Arlington and what isn't. If I understand correctly, for PageLabels Arlington checks against the Table 161 in ISO32000-2:2017. However, there is this additional sentence in the spec for the numbered tree: "The tree shall include a value for page index 0." (see p. 455 and within table 161). I've encountered a file in the wild that was created with a numbered tree not starting with 0 and have build a small synthetic file (attached) based on that where the tree is: /Nums [1 <</S /D>> 2 <</S /r>>]

I know that different PDF readers handle Page Label display with a numbered tree not starting at 0 differently - some just stick to decimal Arabic numerals per default, some interprete the tree as is, ignoring the error. My questions are:

• do you consider the numbered tree as above an error?
• is it considered within scope for the Arlington model to detect these errors that are contained in the spec but outside of the tables describing the dictionaries

I checked the file with Arlington model (via veraPDF's implementation) and it came back as having no deviations.

hello_label_wrong.pdf