Science platforms are made up of (at least) four planks: data formats, services, tools and conventions. I focus here on formats and conventions, specifically the HDF5 format, already used in many disciplines, and the Climate-Forecast and HDF-EOS Conventions. Many science disciplines have already agreed on HDF as the preferred format for storing and sharing data. It is well established in high performance computing and supports arbitrary grouping and annotation. Community conventions are critical for useful data on top of the format. The Climate-Forecast (CF) conventions were created for relatively simple gridded data types while the HDF-EOS conventions originally considered more complex data (swaths). Making simple conventions more complex makes adoption more difficult. Community input and the need for stable data processing systems must be balanced in governance of conventions.