The pdf14 LaTeX package Manuel P\'egouri\'e-Gonnard Starting with TeX Live 2010, the various formats that directly generate PDF default to PDF 1.5. While this allows for more compact documents thanks to objects compression, it can also lead to compatibility issues with some older PDF viewers. This package changes back the version of generated PDF to 1.4 with formats based on pdfTeX or LuaTeX in PDF mode, for documents that need to achieve maximal compatibility with old viewers. If you need to generate maximally compatible documents, you may also be interested in the pdfx package.