The primary standardized format for encoding the output of mass spectrometer instruments is mzML. All instruments write out their primary data in a binary vendor format. Most vendors provide software libraries to read their data files, but these are often only available on the Microsoft Windows platform. In order to facilitate data analysis on any platform, and ensure that data files could always be read, the PSI developed the open XML-based format mzML. Version 1.0 was released in 2008 and a minor fix version 1.1 was released in 2009; version 1.1 has been stable and widely used ever since.