For some purposes, we allow dspecs that do not name a global definition, but a local function. These are of the form
(subfunction name parent)
where parent is another dspec (possibly even a subfunction dspec).
name is a symbol, a list, or a number, but it is not used for anything within the dspec system. A subfunction dspec can be canonicalized and prettified, and passed as an argument to dspec-definition-locations (which will find where parent is defined).
Additionally pseudo-dspecs like this are allowed for top-level forms:
(top-level-form (location <#>))
location is a basic location and <#> identifies the top-level form within that location. These are used as parent dspecs in subfunction dspecs and :inside locations. These dspecs can be canonicalized and prettified, and can be returned as dspecs from the location finders.
LispWorks User Guide and Reference Manual - 13 Feb 2015