Syllables have the maximal structure of (C)(C)V(C). The only possible codas in European Portuguese are , and and in Brazilian Portuguese and . The two rhotic phonemes and contrast only between oral vowels -a phenomenon similar to the Spanish rhotic system-. Elsewhere, their occurrence is predictable by context, with dialectal variations in realization. The rhotic is "hard" (i.e., ) in the following circumstances: It is "soft" (i.e., ) when it occurs in syllable onset clusters (e.g., "atributo"), and written as a single 'r' between vowels (e.g., "dirigir" 'to drive')  The realization of the "hard" rhotic varies significantly across dialects. This restricted variation has prompted several authors to postulate a single rhotic phoneme. and see the soft as the unmarked realization and that instances of intervocalic result from gemination and a subsequent deletion rule (i.e., "carro" > > ). Similarly, argue that the hard is the unmarked realization. In addition to the phonemic variation between and between vowels, up to four allophones of the "merged" phoneme /R/ are found in other positions:  The default hard allophone is some sort of voiceless fricative in most dialects, e.g., , although other variants are also found. For example, a trill is found in certain conservative dialects down São Paulo, of Italian-speaking, Spanish-speaking, Arabic-speaking, or Slavic-speaking influence. The other trill is found in areas of German-speaking, French-speaking, and Portuguese-descended influence throughout coastal Brazil down Espírito Santo, most prominently Rio de Janeiro. The syllable-final allophone shows the greatest variation:  Throughout Brazil, deletion of the word-final rhotic is common, regardless of the "normal" pronunciation of the syllable-final allophone. This pronunciation is particularly common in lower registers, although found in most registers in some areas, e.g., Northeast Brazil, and in the more formal and standard sociolect. It occurs especially in verbs, which always end in R in their infinitive form; in words other than verbs, the deletion is rarer and seems not to occur in monosyllabic non-verb words, such as "mar". Evidence of this allophone is often encountered in writing that attempts to approximate the speech of communities with this pronunciation, e.g., the rhymes in the popular poetry (cordel literature) of the Northeast and phonetic spellings (e.g., "amá, sofrê" in place of "amar, sofrer") in Jorge Amado's novels (set in the Northeast) and Gianfrancesco Guarnieri's play "Eles não usam black tie" (about favela dwellers in Rio de Janeiro).