According to some contemporary Brazilian linguists, Brazilian Portuguese may be a highly diglossic language. This theory claims that there is an L-variant (L for Low, termed “Brazilian Vernacular”), which would be the mother tongue of all Brazilians, and an H-variant (H for High, standard Brazilian Portuguese) acquired through schooling. L-variant represents a simplified form of the language (in terms of grammar, but not of phonetics) that could have evolved from 16th century Portuguese, influenced by Amerindian (mostly Tupi) and African languages, while H-variant would be based on 19th century European Portuguese (and very similar to Standard European Portuguese, with only minor differences in spelling and grammar usage). Mário A. Perini, a Brazilian linguist, even compares the depth of the differences between L- and H- variants of Brazilian Portuguese with those between Standard Spanish and Standard Portuguese. However, his proposal is not widely accepted by either grammarians or academics. Milton M. Azevedo wrote a chapter on diglossia in his monography: Portuguese language (A linguistic introduction), published by prestigious Cambridge University Press, in 2005.
From this point of view, the L-variant is the spoken form of Brazilian Portuguese, which should be avoided only in very formal speech (court interrogation, political debate) while the H-variant is the written form of Brazilian Portuguese, avoided only in informal writing (such as songs lyrics, love letters, intimate friends correspondence). Even language professors many times use the L-variant while explaining students the structure and usage of the H-variant; in essays, nevertheless, all students are expected to use H-variant.
While the L-variant may used in songs, movies, soap operas, sitcoms and other television shows, although, at times, the H-variant is used in historic films or soap operas to make the language used sound more ‘elegant’ and/or ‘archaic’. There is a claim that the H-variant used to be preferred when dubbing foreign films and series into Brazilian Portuguese, but nowadays the L-variant is preferred, although this seems to lack evidence. Movie subtitles normally use a mixture of L- and H-variants, but remain closer to the H-variant.
Most literary works are written in the H-variant. There would have been attempts at writing in the L-variant (such as the masterpiece Macunaíma, written by Brazilian modernist Mário de Andrade and Grande Sertão: Veredas, by João Guimarães Rosa), but, presently, the L-variant is claimed to be used only in dialogue. Still, many contemporary writers like using the H-variant even in informal dialogue. This is also true of translated books, which never use the L-variant, only the H one. Children’s books seem to be more L-friendly, but, again, if they are translated from another language (The Little Prince, for instance) they will use the H-variant only.