Provide reference for OTF tags in the ELisp manual

* doc/lispref/display.texi (Low-Level Font): Provide the canonical
reference URL for OTF tags.

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index d9e93160ea30bcbdce05e37be1642b22623bfc66..61aca5b88a6742d737b966b1a455d02e1cc9b178 100644 (file)
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -3866,7 +3866,10 @@ required; and @code{gpos} is a list of OpenType GPOS feature tag
 symbols, or @code{nil} if none is required.  If @code{gsub} or
 @code{gpos} is a list, a @code{nil} element in that list means that
 the font must not match any of the remaining tag symbols.  The
-@code{gpos} element may be omitted.
+@code{gpos} element may be omitted.  For the list of OpenType script,
+language, and feature tags, see
+@uref{https://docs.microsoft.com/en-us/typography/opentype/spec/ttoreg,
+the list of registered OTF tags}.
 
 @item :type
 @cindex font backend