In the extIPA, indistinguishable/unidentifiable sounds are circled rather than placed in single parentheses. An empty circle, ◯, is used for an indeterminate segment, ◯σ  an indeterminate syllable, Ⓒ a segment identifiable only as a consonant, etc. Full capital letters, such as C in Ⓒ, are used as wild-cards for certain categories of sounds, and may be combined with IPA and extIPA diacritics. For example, ◯   (a circled capital with a voiceless diacritic) indicates an undetermined or indeterminate voiceless plosive. Regular IPA and extIPA letters may also be circled to indicate that their identification is uncertain. For example, ⓚ indicates that the segment is judged to probably be . At least in handwriting, the circle may be elongated into an oval for longer strings of symbols.