A child learning his [her] mother tongue is learning how to name; he [she] is building up a meaning potential in respect of a limited number of socia… - Michael Halliday

I see it as part of the development of the field. I would always emphasize how much I share with other linguists: I've never either felt particularly distinct or wanted to be distinct. I never saw myself as a theorist; I only became interested in theory, in the first place, because, in the theoretical approaches that I had access to, I didn't find certain areas developed enough to enable me to explore the questions that I was interested in.

[Register] is set of meanings, the configuration of semantic patterns, that are typically drawn upon under the specified conditions, along with the words and structures that are used in the realization of these meanings.

The theme is what is being talked about, the point of departure for the clause as message, and the speaker has within certain limits the option of selecting any element in the clause as thematic.