I believe the "can" in each of these should be "must".
That depends on whether you think of it as an enabling modifier or a restricting one. I admit the situation is not entirely clear cut. Specifying multiple modifiers means that you can do each of those. E.g. having cp means hopping as well as capturing get enabled (in a non-final leg), and what is not mentioned (non-capture or moving off board) is not allowed. This is somewhat contradicted by the fact that (in final legs) mc is the default mode. So writing a single m disables c, rather than changin the m rights (and vice versa). But forbidding c is not really the meaning of m, as you can write mc, and that would allow both. (It would just be unnecessary verbose, unless there is a third mode involved, like mce. So the way I look at it is that the modifiers enable what they mention, and do not affect any rights they do not mention (for which I think 'can' is the proper choice). It is just that we have the convention that a pure 'mc' can be omitted.
That depends on whether you think of it as an enabling modifier or a restricting one. I admit the situation is not entirely clear cut. Specifying multiple modifiers means that you can do each of those. E.g. having cp means hopping as well as capturing get enabled (in a non-final leg), and what is not mentioned (non-capture or moving off board) is not allowed. This is somewhat contradicted by the fact that (in final legs) mc is the default mode. So writing a single m disables c, rather than changin the m rights (and vice versa). But forbidding c is not really the meaning of m, as you can write mc, and that would allow both. (It would just be unnecessary verbose, unless there is a third mode involved, like mce. So the way I look at it is that the modifiers enable what they mention, and do not affect any rights they do not mention (for which I think 'can' is the proper choice). It is just that we have the convention that a pure 'mc' can be omitted.