In jazz, unlike tennis, the lines between playing 'in' and 'out' are blurred, there being no umpire to make the call.
For musicians, playing 'out' originally meant simply stepping outside the boundaries set by a composition's harmonic structure.
Latterly, as the late British jazz critic Richard Cook pointed out, the term 'tends to be used as description for any sort of unconventional though not wholly free playing'.
Just how far 'out' jazz can go before it becomes unacceptable varies considerably from listener to listener. Well before he began playing 'free jazz' Ornette Coleman played an 'out' solo during an R&B gig in Baton Rouge, Louisiana, and after the show was beaten up by some members of the audience, who also smashed his saxophone.
Saxophonist Sam Rivers, who died on December 26, was an 'out' player, with roots in gospel and R&B. He started out as an accomplished bebop player who during the 1960s gradually evolved into one of the leading exponents of free jazz.
In 1964, after a stint with Texas bluesman T-Bone Walker, he briefly joined the Miles Davis Quintet replacing George Coleman, but was allegedly too 'out' for Davis and was replaced by Wayne Shorter.
Nothing daunted, Rivers signed with the Blue Note label as a leader and continued to work with other members of the Davis Quintet - drummer Tony Williams, bassist Ron Carter and pianist Herbie Hancock - as well as pianists Jaki Byard and Andrew Hill.
His Blue Note albums walked a delicate line between fashionable hard bop and the more controversial 'free jazz' being pioneered by Coleman and Cecil Taylor.
Rivers went on to work with Taylor, and then in the 1970s again as a leader with both small groups and big bands, extending his scope as a composer, arranger and multi-instrumentalist. He was a pioneer of 'loft jazz' in New York, setting up Studio Rivbea in Lower Manhattan, a space where music deemed insufficiently commercial for most clubs could be played.
He was also a respected jazz educator, and taught and played until his death, aged 88.
'Free jazz' and subsequent dissonant movements have their value and their constituencies, but it is probably fair to say that for most modern jazz fans the outer limits of the acceptable are drawn in the early 1960s recordings of John Coltrane, and in particular 1962's Live at the Village Vanguard.
This landmark live album has been expanded in subsequent editions, but in its original form comprised just three tracks of 'out' playing: Sigmund Romberg's Softly As in a Morning Sunrise and Coltrane's Spiritual, and Chasin' the Trane, a monumental blues which occupied the whole of side two of the vinyl release.
The album received a mixed critical response at the time of release, and it made Coltrane a controversial figure. It is now generally recognised as a classic, and Chasin' the Trane in particular as one of the saxophonist's career-defining performances.
Pianist Allen Youngblood is among the musicians who have been strongly influenced by the album - reviews of his early performances in the US compared him to Coltrane's pianist McCoy Tyner - and intends to include some music influenced by the album in his Kinetic Soundscapes concert programme at Grappa's Cellar on March 21.
'Live at the Village Vanguard is one of my favourite Coltrane recordings. The spirituality with which the music is approached is amazing,' says Youngblood. 'You can hear all the real threads of black American music from the church to the blues in a jazz concept.'
This is the third concert in a series begun last year and, as previously, the band for Kinetic Soundscapes will comprise Youngblood on keyboards, Eugene Pao on guitar, Paul Candelaria on bass, Robbin Harris on drums, and Blaine Whittaker on alto saxophone.
The programme will consist mostly of original compositions, reflecting either the Coltrane influence or Youngblood's Caribbean heritage. Previous Kinetic Soundscapes performances have sold out quickly, so advance booking is advisable. Tickets are available from Grappa's Cellar (Tel: 2521 2322) at HK$288, and showtime is 9pm.
Fans of swing jazz should head to City Hall on Tuesday for the annual celebration of big band jazz entitled 'Swing For All', featuring the Saturday Night Jazz Orchestra and Lando Bernal's Big Broad Band, plus guests. The show begins at 7.30pm with a free foyer performance by the Middle School Big Band. Tickets for the main programme, which starts at 8pm cost HK$150, HK$220 and HK$280 from Urbtix.
Three classic 'out' albums.
Jazz Advance (Blue Note, 1956): Cecil Taylor's manifesto - jazz which is not yet free, but straining at the leash. Still listenable for a bop fan but already asking awkward questions.
Fuchsia Swing Song (Blue Note, 1964): Sam Rivers' Blue Note debut as a leader featuring vintage performances from Rivers himself, Jaki Byard, Ron Carter and Tony Williams. Edgy but accessible.
The Complete 1961 Live at the Village Vanguard Recordings (Impulse, 1997): A four-disc set including all the music recorded over four nights at the Village Vanguard in November 1961.