only; if the clipboard holds other types of data, Emacs treats the
clipboard as empty.
+@cindex scrap support (for Mac OS)
+On Mac OS, selection-like data transfer between applications is
+performed through a mechanism called @dfn{scraps}. The clipboard is a
+particular scrap named @code{com.apple.scrap.clipboard}. Types of scrap
+data are called @dfn{scrap flavor types}, which are identified by
+four-char codes such as @code{TEXT}. Emacs associates a selection with
+a scrap, and a selection type with a scrap flavor type via
+@code{mac-scrap-name} and @code{mac-ostype} properties, respectively.
+
+@example
+(get 'CLIPBOARD 'mac-scrap-name)
+ @result{} "com.apple.scrap.clipboard"
+(get 'com.apple.traditional-mac-plain-text 'mac-ostype)
+ @result{} "TEXT"
+@end example
+
+Conventionally, selection types for scrap flavor types on Mac OS have
+the form of @acronym{UTI, Uniform Type Identifier} such as
+@code{com.apple.traditional-mac-plain-text},
+@code{public.utf16-plain-text}, and @code{public.file-url}.
+
@defopt x-select-enable-clipboard
If this is non-@code{nil}, the Emacs yank functions consult the
clipboard before the primary selection, and the kill functions store in
the clipboard as well as the primary selection. Otherwise they do not
access the clipboard at all. The default is @code{nil} on most systems,
-but @code{t} on MS-Windows.
+but @code{t} on MS-Windows and Mac.
@end defopt
@node Drag and Drop