Update runtime files
diff --git a/runtime/indent/dtd.vim b/runtime/indent/dtd.vim
index 30c06aa..c2b3c0c 100644
--- a/runtime/indent/dtd.vim
+++ b/runtime/indent/dtd.vim
@@ -1,12 +1,15 @@
" Vim indent file
-" Language: DTD (Document Type Definition for XML)
-" Previous Maintainer: Nikolai Weibull <now@bitwi.se>
-" Latest Revision: 2011-07-08
+" Language: DTD (Document Type Definition for XML)
+" Maintainer: Doug Kearns <dougkearns@gmail.com>
+" Previous Maintainer: Nikolai Weibull <now@bitwi.se>
+" Last Change: 24 Sep 2021
setlocal indentexpr=GetDTDIndent()
setlocal indentkeys=!^F,o,O,>
setlocal nosmartindent
+let b:undo_indent = "setl inde< indk< si<"
+
if exists("*GetDTDIndent")
finish
endif