Notes for topal - reproducible builds result

Version annotated: 81-2
Identified issues:
Identifier: timestamps_in_pdf_generated_by_latex
URL https://wiki.debian.org/ReproducibleBuilds/TimestampsInPDFGeneratedByLaTeX
Description PDF files generated with pdftex and pdflatex will contain CreationDate and
ModDate set to the current date and time.
Identifier: different_encoding
Description Files were built with different encoding (non-UTF-8 vs. UTF-8).
Identifier: fonts_in_pdf_files
Description The internally used names/identifiers of fonts embedded into PDF files varies.
The order of embedded fonts can also be different.
.
The order is only different if the date differs (set by TZ environment
variable for example). If the date is the same, then the font name
is reproducible. Difference in hour/minute/second resolution seems
to be irrelevant.
.
The font name occurs in the /BaseFont field and in the /Fontname field.
The name is of the form XXXXXX+YYY where the XXXXXX part is the one that
varies and is called the subset_tag. It is generated in
texk/web2c/pdftexdir/utils.c function make_subset_tag() from an MD5 sum
over the font glyphs.
 

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