  In this paper, we share our experience of developing a hybrid execution
environment for computer-interpretable guidelines (CIGs) in PROforma. The
proposed environment is part of the CAPABLE system which provides coaching for
cancer patients and decision support for physicians. It extends a standard
PROforma execution engine - Deontics Engine (DE) - with additional components
that act as wrappers around DE, allow handling of non-standard tasks, and
facilitate integration with the rest of the CAPABLE system. This yields a
hybrid environment in which the standard engine and specialized components must
be interfaced together by some intervening layer. In the CAPABLE system this
has been achieved by defining a set of specialized meta-properties which are
attached to data and tasks in the PROforma CIGs to specify the interface
between engine and components.
