(Disclaimer) In my limited experience of using MIDI, I offer the following:
I don't think it's a MIDI Control Change (CC) number.
It's probably a MIDI Machine Code (MMC) parameter value which would be used for starting and stopping device "transport".
The MIDI universal MMC values for start and stop are 01 & 02, which are not a CC numbers but MMC mode parameters.
STOP (01)
PLAY Play (02)
These values are communicated on MIDI channel 127 which is one of the MIDI channels reserved for Channel Mode Messages.
The Arturia BeatStep Hardware, which talks natively to iSpark (give one a go, they are cheap), definately uses MMC 01 & 02 on channel 127 for transport control - start & stop, it's stated in the manual on page 37.
This strongly implies that iSpark would be listening on channel 127 for MMC 01 & 02 to start and stop.
http://downloads.arturia.com/products/beatstep/manual/BeatStep_Manual_1_0_1_EN.pdfThe BlueBoard can send MIDI Program Changes and MIDI Control Changes according to the website.
That doesn't specifically mean transport messages, but instead implies you can change a program,
so maybe you can't start or stop iSpark because BlueBoard doesn't do MMC, but you might be able to change the preset or pattern on iSpark with the BlueBoard.
I see on the IK website that BlueBoard does on / off, but I believe that is a MIDI Control Change (MCC), to toggle just switches on or off, like reverb or mute.