Update runtime files.
diff --git a/runtime/doc/undo.txt b/runtime/doc/undo.txt
index 2ada2a6..b6c9809 100644
--- a/runtime/doc/undo.txt
+++ b/runtime/doc/undo.txt
@@ -1,4 +1,4 @@
-*undo.txt* For Vim version 8.1. Last change: 2014 May 24
+*undo.txt* For Vim version 8.1. Last change: 2019 Jan 04
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -259,6 +259,12 @@
When the file is encrypted, the text in the undo file is also crypted. The
same key and method is used. |encryption|
+Note that text properties are not stored in the undo file. You can restore
+text properties so long as a buffer is loaded, but you cannot restore them
+from an undo file. Rationale: It would require the associated text property
+types to be defined in exactly the same was as before, which cannot be
+guaranteed.
+
You can also save and restore undo histories by using ":wundo" and ":rundo"
respectively:
*:wundo* *:rundo*