Supported type tags in CNMAT OpenSoundControl external in max/msp

Does the CNMAT OpenSoundControl external support 64-bit double precision floats?

according to this link, it does, but I have had no luck getting any output sending it an
osc message with a "d" in it.

Is the source code for this external available anywhere? I would ideally like to dig into it and see what format it
expects a double in, (endianess etc), if at all.

I've done a fair bit of googling, and digging around on the CNMAT website,
but can't find any more information about it.