In the current implementation a continuation leg would always need a directional modifier, as the default is 'every direction except back', just as in the 'a-notation' to which it is converted by a simple pre-processor. We could change that default into 'forward' (= outward), though. Then the Pegasus would indeed be [N?R], rather than [N?fR].
Note that the ? to make the continuation optional is only needed to include the first step, so one can write [F?R] for the Griffon rather than F[F-R]. Since the Octopus is not able to stop at the initial squares of the path (which by definition consists of the squares where it can be blocked), using the hyphen would be more natural: [F-W-R][W-F-B].
In the current implementation a continuation leg would always need a directional modifier, as the default is 'every direction except back', just as in the 'a-notation' to which it is converted by a simple pre-processor. We could change that default into 'forward' (= outward), though. Then the Pegasus would indeed be [N?R], rather than [N?fR].
Note that the ? to make the continuation optional is only needed to include the first step, so one can write [F?R] for the Griffon rather than F[F-R]. Since the Octopus is not able to stop at the initial squares of the path (which by definition consists of the squares where it can be blocked), using the hyphen would be more natural: [F-W-R][W-F-B].