Am Fri, 28 Jul 2023 19:25:54 +0200 schrieb LARONDE Thierry: >> Note that in order to do file testing by expansion (which we want for >> various expl3 functions), we *have* to avoid \openin and that realistically >> means \(pdf)filesize is the best option. > > Why in this case not having requested a \filefind primitive, Adding new primitives to all engines LaTeX supports is not easily done, it can take a year or more and even if they are finally implemented we would have to provide fallbacks for older engines. So why should we do this work if a suitable primitive is already present in all engines engines we test? Imho the question is more the other way round: why did you implemented the primitive differently to the other engines? As you explicitly document "but no extension is implicit" you must have been aware that one must consider this case and that you are deviating here. -- Ulrike Fischer http://www.troubleshooting-tex.de/