The way the stOTTR spec is written now, it is sometimes unclear whether the terms reference a stOTTR specific language construct or whether we are describing how a mOTTR specific construct is serialised. For example:
A template instance consists of a template reference and a possibly empty list of arguments.
Are we here introducing a new syntactic construct called "template instance", or is this stating how the mOTTR term "template instance" is serialized? Further down we have
An argument is a term, possibly prefixed by the "listExpand" marker ++.
So here the word "argument" means something else than mOTTR's "argument", as in mOTTR "argument" is just a (OTTR) term.
I think we should clearly distinguish between stOTTR language constructs and the mOTTR/rOTTR construct that is being serialised.