Creating SND_UD long frames

[blagasz]

I could not figure out how to create and SND_UD long frame. The docs say:

6.4.2 Writing Data to a Slave The master can send data to a slave using a SND_UD with CI-Field 51h for mode 1 or 55h for mode 2. Note that the data structure in such a write telegram has been changed in contrast to previous definitions by means of leaving out the fixed data header of 12 byte.

Is it possible to do that with the current implementation? As far as I understands it needs a 13 bit header unless it starts with 0x78. I am not sure if I modify the code to allow 0x51 as well it won't break it somewhere else.

Thanks for your help!