V06a refers to V06 transmissions with more than one message. At the end of each message, instead of the 3-figure group of unknown purpose and the amount of 5-figure groups in the message, the transmission ID is repeated for one minute, then the standard message procedure continues. The final message ends with "00000".

V06a was heard only once - on Monday, August 16th, 1999 at 07:00 UTC on 16342kHz: ID 362, 84-group message #534 and 85-group message #535.^[1]

References

1. ENIGMA Newsletter #18 (January 2000), p. 29 - read a scanned version here