Alist mapping loaded file names to symbols and features.
Each alist element should be a list (FILE-NAME ENTRIES...), where
FILE-NAME is the name of a file that has been loaded into Emacs.
The file name is absolute and true (i.e. it doesn't contain symlinks).
As an exception, one of the alist elements may have FILE-NAME nil,
for symbols and features not associated with any file.
The remaining ENTRIES in the alist element describe the functions and
variables defined in that file, the features provided, and the
features required. Each entry has the form `(provide . FEATURE)',
`(require . FEATURE)', `(defun . FUNCTION)', `(autoload . SYMBOL)',
`(defface . SYMBOL)', or `(t . SYMBOL)'. Entries like `(t . SYMBOL)'
may precede a `(defun . FUNCTION)' entry, and means that SYMBOL was an
autoload before this file redefined it as a function. In addition,
entries may also be single symbols, which means that SYMBOL was
defined by `defvar' or `defconst'.
During preloading, the file name recorded is relative to the main Lisp directory. These file names are converted to absolute at startup.