The DDS XRCE (“eXtremely Resource Constrained Environments” because all OMG specifications need a cool acronym) specification isn’t even close to finished yet. The RFP is available but you have to be an OMG member to get the working documents, unless someone involved is willing to provide them. When the specification is adopted, that becomes publicly available.
As seems to happen a lot with the DDS specs these days, the RTI/eProsima/Twin Oaks camp and the PrismTech camp have produced their own versions of the XRCE specification and are struggling to reconcile them into a single specification that the OMG can adopt. I won’t wade into the debate over which is better, but I’ll let you draw your own conclusions from the fact that one of the two camps only has one company it it. 
I hope it’s not going to be the RPC for DDS spec all over again; the arguments over that could be heard in other meeting rooms. But it seems likely that it will be a year and a half or more before the final specification is released.