Live, the group sometimes breaks compositions into sections which combine different players, who improvise with each other, referring to the composition's structure to varying degrees. Holland's writing--and that of his bandmates, who share a similar interest in mood and complex meter--lays out problems for the improvisers, and their spontaneously played ideas give them the seeds for new written pieces.

"There is a symbiotic relationship between one's work as a composer and as an improviser as exemplified by the work of John Coltrane," wrote Holland via email. "The compositions present the group with musical and emotional settings which will permit and encourage the development of certain improvisational ideas, known and unknown. These developments, in turn, give you ideas for the next composition. This is the approach for most of my writing."

During the tour, the group will also present new compositions that it plans to record this fall for a 2001 ECM release, Holland wrote. Holland and his bandmates, who also contribute material to the quintet's albums, had tunes in their 1998 road book which turned up on 1999's "Prime Directive."

As a bass player who has developed very tight relationships with drummers over the years (Jack DeJohnette, Marvin "Smitty" Smith and now Kilson), Holland is intensely interested in new rhythms. Holland's piece "Make Believe" on "Prime Directive" uses a 5/4 structure which he learned from Anouar Brahem, a Tunisian oud player with whom Holland has toured.

''Anouar introduced me to this type of rhythm--which alternates two groups of five beats, first 3 & 2 and then 2 & 3--that exists in Arab music,'' Holland said in a statement about the recording. ''The last time I was on tour with him, our final concert was in his hometown of Tunis, and I was fascinated by a wonderful musician who was performing while we were eating dinner one night. He saw me watching him and mimed the rhythm structure, which turned out to be the same one Anouar had showed me. Shortly thereafter I was in China with the quintet, and while I was demonstrating the rhythm to [drummer] Billy [Kilson], I came up with the structure the song starts out with. We'd been to the Forbidden City and other fantastic, almost make believe places, and that's what inspired the song's title.''

A key element of the quintet is vibraphonist Steve Nelson, a mallet percussionist who can play both lines and chords, but serves as an instrumental voice more than as a rhythm section instrument. Holland is one of the few bandleaders now recording regularly who has made the vibes a key part of his group's music.

Besides hiring Nelson for his approach, Holland wrote, ''I like the vibes as an instrument because it belongs to the percussion family and because of the texture and openness it creates."

Holland, born in England in 1946, has played almost every type of jazz--early fusion, open-form music and post-bop--since he first came on to the scene with Miles Davis in 1968. A leader and sideman on over 30 ECM albums, Holland appeared on Terence Blanchard's latest album "Wandering Moon" (Sony Classical).