The multline environment is a variation of the equation
environment used for equations that don't fit on a single line. The
first line of a multline will be at the left margin and the last
line at the right margin, except for an indention on both sides in the
amount of multlinegap. Intermediate lines will be centered
independently within the display width. However, it's possible to force
a line to the left or right with commands shoveleft,
shoveright. These commands take the entire line as an argument, up
to but not including the final
; for example
\begin{multline}
\framebox[.65\columnwidth]{A}\\
\framebox[.5\columnwidth]{B}\\
\shoveright{\framebox[.55\columnwidth]{C}}\\
\framebox[.65\columnwidth]{D}
\end{multline}
The value of multlinegap can be changed using /'s setlength and addtolength commands. If the multline contains more than two lines, any lines other than the first and last will be centered individually between the margins (except when the fleqn option is in effect).