The initial value of
*binary-file-type* depends on the host CPU and the LispWorks implementation. See Naming conventions for FASL files.
*binary-file-type* is the file type that
require recognize as a binary (FASL) file (in addition to any additional file types in *binary-file-types*).
Normally you should not set
*binary-file-type*. If you need to load files with another type, push that type on to *binary-file-types*.
LispWorks User Guide and Reference Manual - 20 Sep 2017