The first line of the equation will be set at the left margin, the last line on the right margin, and all possible other lines will be centered. This behaviour can be changed with the
\shoveright commands, that take entire lines as their argument, and place them at the left, resp. right margin. A
multline environment thus contains no alignment points
&. The environment gets a single equation number that is placed at the first line, while the
reqno option of the
amsmath package shifts the equation number to the last line.
For a similar multi-line equation that shall be part of a larger equation the
mathtools package provides the