The variable *record-source-files*
controls whether locations of definitions are recorded in the internal tags database.
*record-source-files*
was documented in the lispworks
package in LispWorks 4.3 and earlier. Although it is currently still available there, this may change in future releases and you should now reference it via the dspec
package.
LispWorks User Guide and Reference Manual - 13 Feb 2015