MIL-STD-883 is basically a guide to quality testing procedures for integrated circuits. If a manufacturer performs the tests described in
883 to semiconductors off the manufacturing line (and the components pass the tests), they may be marked as 883 components. Because of the extra testing of each component (not statistical-based tests) the components are shipped with a known higher quality (and thus implied reliability) than the equivalent commercial components. For example: you know that an 883 component will probably not fail the first time you heat it up to a Tj of 125 degC. because it has already experienced that level of stress for a known period of time.JAN, JANTX, JANTXV, and JANS are quality levels for discrete semiconductors. The manufacturer's processes and post-production testing allow these components to be marked with the various quality levels. The order given indicates higher levels of screening and testing, the highest being 'S' or 'space' quality.
SMD stands for Standard Military Drawing. It is a relatively recent development, simply used to standardize component data sheets. For example: several manufacturers make part 'X' (sometimes with the same die), and all have their own data sheets, with their own particular formats, information, etc. The SMD drawing takes all of the information that is important to the circuit designers and analysts and puts it in a common format.