XTCE12 — lack of Union construct (MER + ASIST)

MER supports a Union construct because their abstract data types live past decomm. ASIST also supports the same idea – that an abstract data type onboard the spacecraft MAY live past decomm. Although it is possible to let multiple parameters overlap, in a sense allowing for a Union in XTCE. The issue arises that validating software cannot differentiate this with a bug in a container specification. A union tag or element of some sort is needed.

Programming construct does not fit current data model, defer to future revision

Not all ground systems support the union construct in the decommutated data. By specifying overlapping locationInContainer positions, the effect of the union can be achieved in XTCE. This feature request is being deferred to a future revision.