The text quoted in this comment is section 4.2 from RFC 2553
("Basic Socket Interface Extensions for IPv6")
https://tools.ietf.org/html/rfc2553#section-4.2
RFC 2533 ("A Syntax for Describing Media Feature Sets") clearly has
nothing to do with this function.
Index: lib/libc/net/if_indextoname.c
===================================================================
RCS file: /var/cvs/src/lib/libc/net/if_indextoname.c,v
retrieving revision 1.11
diff -u -p -r1.11 if_indextoname.c
--- lib/libc/net/if_indextoname.c 23 Oct 2015 13:09:19 -0000 1.11
+++ lib/libc/net/if_indextoname.c 10 May 2018 12:42:24 -0000
@@ -35,7 +35,7 @@
#include <errno.h>
/*
- * From RFC 2533:
+ * From RFC 2553:
*
* The second function maps an interface index into its corresponding
* name.
