Infographics of Joint Service Specification ( JSS 0251 ) – Code And Pixels JSS 251 is a defence documentation standard. To make it simpler, whenever we buy some household item, be it a fridge or AC, we get a user manual. If you look closely, each company follows their documentation structure or pattern and content flow. There will not be any similarities in formatting or layout. Every OEM has their separate documentation teams and they design in their way.