Re-reading Marie Clay's 'What did I write?' I discover that her argument about mark-making and writing principles is more complex than I remembered - there are at least 7 and that's if you don't count the sign concept and the message concept. Way back - was it 1930 (?) Vygotsky wrote in Mind and Society about young children's meaningful mark-making. Although Clay doesn't reference this, what she is really doing is elaborating on Vygotsky's observations. Now we need to refine the idea of writing principles in the light of changing technology.