This is called the Julian (or Ordinal; I don't think there is a difference) calendar and is in wide use in (at least) parts of the US military for tracking thin

This is called the Julian (or Ordinal; I don't think there is a difference) calendar and is in wide use in (at least) parts of the US military for tracking things. Actually, looking it up now it looks like the usage of the name "Julian" is due to the way the old tracking systems were programmed and used "JDATE" or similar. Nowadays it's just burned in habit that it's called the Julian Date.