4.3.9 EXTRACT Class says, "the generic parameters select which kind of specification and content the Extract carries."
The trouble is, EXTRACT does not have any generic parameters.
Furthermore, it's not clear why there would be a generic parameter for the content anyway, given that there is no 'content' attribute. There's a 'content' attribute on EXTRACT_CHAPTER, but not on EXTRACT.
I was looking at the 1.0.2 release. In the TRUNK, this has moved to 4.3.8.
In the TRUNK, 4.3.9 has a new (but related) problem in EXTRACT_CHAPTER:
Invariants Content_valid: content /= Void
The 'content' attribute does not exist any more in EXTRACT_CHAPTER either.
I would recommend this be resolved by a documentation change - SPECRM-24.