Wait... I never saw request in lower case in the Zope environment.
"request" is the (more modern) spelling which comes from
(Zope 3) BrowserView conventions. Those views typically
use the attributes context and request to access the
adapted objects (views are (under the hood) adapters for an object
and the request).
"REQUEST" is the (older) spelling used to access the request object
via acquisition. Thus, in a BrowserView, you typically
have self.request is self.context.REQUEST.