What do these constants mean?

[ghost]

Hi!

I can't work out what
TRANS_MSB_SHIFT,
RECE_MSB_SHIFT and
MSB_RIGHT do.
They all seem a single bit value (true or false).
I guess MSB_RIGHT is either most significant bit/byte right, but I'm not sure which one of the two, and applied to what, each 16/24 bit channel value?
And I haven't even got a guess for TRANS_MSB_SHIFT and RECE_MSB_SHIFT :)

Help? :)

I'm also not sure what BITS_MOD does, but that's less interesting I think :)