http://sn.1w6.org/file/lnxw48-20150531T022215-g4ukccg.html
@bobjonkman @jrm Okay, now I found the context. In #LibreOffice Writer, click File → Export as PDF ... → and under "General" tab, click PDF/A-1a to produce open-standard #PDF file. PDF/A is standardized format for Archiving, so a lot of proprietary extras are locked out as incompatible.