\version "2.17.26"

\include "LilyJAZZ.ily"

stemOff = { \override Staff.Stem.stencil = ##f }
stemOn  = { \revert Staff.Stem.stencil }

improvMusic = \relative b' {
    \improvisationOn \stemOff
    b4 b b b  | b b b b
    b4 b b b  | b b b b
    \stemOn \improvisationOff
} % improvMusic

jazzMusic = \relative b' {
    \jazzOn \stemOff
    b4 b b b  | b b b b
    b4 b b b  | b b b b
    \stemOn \jazzOff
} % jazzMusic

\markup "jazzOn wrapped around improvMusic:"
\score {
  \new Staff { \jazzOn \improvMusic \jazzOff }
}

\markup "improvisationOn wrapped around jazzMusic:"
\score {
  \new Staff { \improvisationOn \jazzMusic \improvisationOff }
}