As all of us use GPS systems to navigate across the world or just in your city, “degré zéro” might nowadays be associated first of all with the prime meridian 0° longitude, which runs through Greenwich near London and around the globe.
In « Le degré zéro de l’écriture », Roland Barthes (1953) challenges the bourgeois kind of writing of literature. He introduced the pertinent distinction of the verticality of writing styles in the sense of social classes as well as the horizontal form of spoken language He further distinguished écriture as a person’s style which is embedded into the historical and social context of her/his time. As a radical change, Barthes proposed to use scriptor instead of writer as the latter expression is too much loaded with the historical package of the person. Barthes inserts the scriptor as écrivain into her/his time and insists on the intellectual and social context of writing or the author.
As the scriptor (p. 26) does not escape to become a writer « écrivain «, the degree zero de l’écriture postulates a homogeneous society, which obviously is an ill-conceived vision of reality. Language and texts, therefore, are not universal in kind, but bound to situations, which are defined in historical time and space (p. 67). Semiotics was a major field of his analyses of literature and language.
Whereas in a talk you might focus on the person you are talking to, in a written text the other person is « the many » readers, wherever they are and maybe at a much later time as well. There is a qualitative difference and yet modern “voice to text” transcription makes all spoken words immediately available as written document or “compte rendu”. (Source: Roland Barthes: De la parole à l’écriture. in Le grain de la voix, Entretien 1962-1980. p. 12).
Let’s watch our language as we follow the longitude or latitude around the globe and even small deviations from degree zero matter a lot. 
Research Teaching Consulting