The return value
in most cases. It will be
only when building an intermediate image for the purpose of building a universal binary, either by save-universal-from-script or the Application Builder (see the
LispWorks IDE User Guide
This is useful if there are some configuration that should be done only in a universal binary image but not in a mono-architecture ("thin") image. Whether the intermediate image will be the Intel or the PowerPC part of the universal binary can be determined by checking *features*.
LispWorks User Guide and Reference Manual - 21 Dec 2011