selection-converter-alist

selection-converter-alist is a variable defined in `C source code'.
Its value is shown below.

Documentation:
An alist associating X Windows selection-types with functions.
These functions are called to convert the selection, with three args:
the name of the selection (typically `PRIMARY', `SECONDARY', or `CLIPBOARD');
a desired type to which the selection should be converted;
and the local selection value (whatever was given to
`x-own-selection-internal').

The function should return the value to send to the X server
(typically a string). A return value of nil
means that the conversion could not be done.
A return value which is the symbol `NULL'
means that a side-effect was executed,
and there is no meaningful selection value.

Value:

((TEXT . xselect-convert-to-string)
 (COMPOUND_TEXT . xselect-convert-to-string)
 (STRING . xselect-convert-to-string)
 (UTF8_STRING . xselect-convert-to-string)
 (TARGETS . xselect-convert-to-targets)
 (LENGTH . xselect-convert-to-length)
 (DELETE . xselect-convert-to-delete)
 (FILE_NAME . xselect-convert-to-filename)
 (CHARACTER_POSITION . xselect-convert-to-charpos)
 (LINE_NUMBER . xselect-convert-to-lineno)
 (COLUMN_NUMBER . xselect-convert-to-colno)
 (OWNER_OS . xselect-convert-to-os)
 (HOST_NAME . xselect-convert-to-host)
 (USER . xselect-convert-to-user)
 (CLASS . xselect-convert-to-class)
 (NAME . xselect-convert-to-name)
 (ATOM . xselect-convert-to-atom)
 (INTEGER . xselect-convert-to-integer)
 (SAVE_TARGETS . xselect-convert-to-save-targets)
 (_EMACS_INTERNAL . xselect-convert-to-identity))