standard or soprano ukulele is C6 tuning: G4–C4–E4–A4, which is often remembered by the notes in the "My dog has fleas" jingle (see sidebar). The G string is tuned an octave higher than might be expected, so this is often called "high G" tuning. This is known as a "reentrant tuning"; it enables uniquely close-harmony chording. The table below shows a pitch's name found over the four strings of a ukulele in standard tuning, from the nut (zero), to the fifteenth fret. More rarely used with the soprano ukulele is C6 linear tuning, or "low G" tuning, which has the G in sequence an octave lower: G3–C4–E4–A4, which is equivalent to playing the top four strings (DGBE) of a guitar with a capo on the fifth fret. Another common tuning for the soprano ukulele is the higher string-tension D6 tuning (or simply D tuning), A4–D4–F4–B4, one step higher than the G4–C4–E4–A4 tuning. Once considered standard, this tuning was commonly used during the Hawaiian music boom of the early 20th century, and is often seen in sheet music from this period, as well as in many method books through the 1980s. D6 tuning is said by some to bring out a sweeter tone in some ukuleles, generally smaller ones. D6 tuning with a low fourth string, A3–D4–F4–B4, is sometimes called "Canadian tuning" after its use in the Canadian school system, mostly on concert or tenor ukuleles, and extensive use by James Hill and J. Chalmers Doane. Whether C6 or D6 tuning should be the "standard" tuning is a matter of long and ongoing debate. There are historic and popular ukulele methods that have used each. For the concert and tenor ukuleles, both reentrant and linear C6 tunings are standard; linear tuning in particular is widely used for the tenor ukulele, more so than for the soprano and concert instruments. The baritone ukulele usually uses linear G6 tuning: D3–G3–B3–E4, the same as the highest four strings of a standard 6-string guitar. Bass ukuleles are tuned similarly to the bass guitar and double bass: E1–A1–D2–G2 for U-Bass style instruments (sometimes called contrabass), or an octave higher, E2–A2–D3–G3, for Ohana type metal-string basses. Sopranino ukulele tuning is less standardized. They are usually tuned re-entrantly, but frequently at a higher pitch than C; for example, re-entrant G6 tuning: D5–G4–B4–E5. As is commonly the case with string instruments, other tunings may be preferred by individual players.