Re: [patch] ox-latex.el: Add `LATEX_PRE_HEADER' keyword

["Juan Manuel Macías" <maciaschain@posteo.net>]

Max Nikulin writes:

> On 17/09/2023 01:00, Juan Manuel Macías wrote:
>> 
>> [1] A longer example to export to a pdf that has pdf-x compliance, with
>> the pdfx package:
>> 
>> \providecommand{\pdfxopts}{x-1a}
>> \begin{filecontents*}{\jobname.xmpdata}
>>    \Title{Some Title}
>>    \Author{Author}
>>    \Language{es-ES}
>>    \Keywords{keywords}
>>    \Publisher{publisher}
>> \end{filecontents*}
>> \documentclass{...
>
> Perhaps you have in mind other cases, but I am unsure concerning this 
> one. However I have tried only setting metadata for hyperref only, so I 
> may miss some important aspects.
>
> First of all, I was unaware of .xmpdata and, trying to get more info, I 
> have found hyperxmp that declares to reuse data from \hypersetup without 
> extra files and without the requirement to add settings before 
> \documentclass.

According to the pdfx package documentation
(https://www.ctan.org/pkg/pdfx), p. 6 (at the bottom of the page)/7:

---
Warning: The \jobname.xmpdata file may be included in the main document
source, within a {filecontents*} environment, provided this comes before
the \documentclass command, as follows[...]
---

> Do you need to add commands before \documentclass because you are using 
> custom classes that loads a lot of packages, so there is no chance to 
> specify various options after \documentclass, but before specific 
> packages are loaded?

Apart from the previous case, there are other varied cases (as I
mentioned) in which it is necessary to put code before documentclass.
For example, the newpax package, to preserve the internal links of a pdf
included in the document, requires putting commands like
\DocumentMetadata{ } before documentclass.

-- 
Juan Manuel Macías

https://juanmanuelmacias.com

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