You've probably already seen this, but here is the description of SCD from the DSM-5 workgroup:
There has been a lot of press lately about how the DSM-5 criteria for ASD will exclude a certain percentage of people who currently have Aspergers or PDD-NOS diagnoses. But many doctors feel that most of those individuals will likely qualify for the SCD diagnosis. It's basically for people who have the social and pragmatic language impairment, but not the sensory or repetitive behaviors.
It actually sounds similar to the diagnosis of Semantic Pragmatic Language Disorder, which is used in the UK but is not recognized as a diagnosis here in the US. There are some good articles on SPLD available on the web, so you might find it helpful to do a web search on that.
Good luck for your IEP meeting! I hope it goes smoothly.