words), a tie bar can be used for liaison, as in the French combination les amis . The liaison tie is also used to join lexical words into phonological words, for example hot dog . A Greek sigma, , is used as a wild card for 'syllable', and a dollar/peso sign, , marks a syllable boundary where the usual fullstop might be misunderstood. For example, is a pair of syllables, and is a syllable-final vowel. Components Typical model In the typical theory of syllable structure, the general structure of a syllable (σ) consists of three segments. These segments are grouped into two components: Onset (ω) a consonant or consonant cluster, obligatory in some languages, optional or even restricted in others Rime (ρ) right branch, contrasts with onset, splits into nucleus and coda Nucleus (ν) a vowel or syllabic consonant, obligatory in most languages Coda (κ) a consonant or consonant cluster, optional in some languages, highly restricted or prohibited in others The syllable is usually considered right-branching, i.e. nucleus and coda are grouped together as a "rime" and are only distinguished at the second level. The nucleus is usually the vowel in the middle of a syllable. The onset is the sound or sounds occurring before the nucleus, and the coda (literally 'tail') is the sound or sounds that follow the nucleus. They are sometimes collectively known as the shell. The term rime covers the nucleus plus coda. In the one-syllable English word cat, the nucleus is a (the sound that can be shouted or sung on its own), the onset c, the coda t, and the rime at. This syllable can be abstracted as a consonant-vowel-consonant syllable, abbreviated CVC. Languages vary greatly in the restrictions on the sounds making up the onset, nucleus and coda of a syllable, according to what is termed a language's phonotactics. Although every syllable has supra-segmental features, these are usually ignored if not semantically relevant, e.g. in tonal languages. Tone (τ) may be carried by the syllable as a whole or by the rime Chinese model In Chinese syllable structure, the onset is replaced with an initial, and a semivowel or liquid forms another segment, called the medial. These four segments are grouped into two slightly different components: Initial (ι) optional onset, excluding sonorants Final (φ) medial, nucleus, and final consonant Medial (μ) optional semivowel or liquid Nucleus (ν) a vowel or syllabic consonant Coda