Definition of Tech Writer, was STC is broken

[jlshaeffer at aol.com]

 I think the only definition that can cover all the nuances would emphasize that Tech Writers are adept at using one or more specialized vocabularies ("jargons" in a non-pejorative sense) as well as standard, generally understood jargon-free language. For example, when documenting software products one uses programmer-speak to communicate with developers and customer-speak to communicate with customers. It may be that neither of these is standard English (or whatever language). 
As for tech writing vs. business writing, I'd just comment that business writing is not limited to persuasive or marketing pieces. SOPs, SOX,? and "Policies and Procedures" are counter examples that spring to mind. (They also provide examples of tech writers being adept at using specialized vocabulary. They'd better, since I picked them, right?)

Jim