Principles or rules for guiding decisions about identifying or designing things or solving problems usually apply in some contexts but not in others. For instance, the rule "don't stand up in the boat" is tremendously important for a person in a canoe, but wouldn't be very helpful to the same person on an ocean liner.
Examples: Do these criteria apply to all plants, or just to flowering plants? Does this law apply to everyone, or just to minors? Does this strategy work in bear markets or only in bull markets? Does this guideline apply to screen design as well as print page design?