Halliday & Matthiessen (2014: 135):
The most fundamental types of speech role, which lie behind all the more specific types that we may eventually be able to recognise, are just two: (i) giving, and (ii) demanding. Either the speaker is giving something to the listener (a piece of information, for example, as in Boof keeps scaring me) or he is demanding something from him (as in just push him off; when [has Boof bit you]?).