In CDA R2, the classCode "TRNS" is a valid classCode for a general Act. However when an Act is under an Entry (as it is in Transport), the list of valid classCodes is constrained and TRNS is not part of this subset.
This problem is significant, but not majorly so, because the vocabulary used for code will indicate that this is some form transport act, regardless of the code system used. The reciever may not understand the code system, which may make it difficult to location transport acts without knowledge of the template identifiers. Regional extensions should constrain the code system to use an appropriate value set to support interoperability.