diff --git a/runtime/doc/vim9.txt b/runtime/doc/vim9.txt
index 385238b..e650b13 100644
--- a/runtime/doc/vim9.txt
+++ b/runtime/doc/vim9.txt
@@ -94,8 +94,20 @@
 	def CallMe(count: number, message: string): bool
 - Call functions without `:call`: >
 	writefile(['done'], 'file.txt')
-- You cannot use old Ex commands `:xit`, `:t`, `:k`, `:append`, `:change`,
-  `:insert`, `:open`, and `:s` or `:d` with only flags.
+- You cannot use old Ex commands:
+	`:Print`
+	`:append`
+	`:change`
+	`:d`  directly followed by 'd' or 'p'.
+	`:insert`
+	`:k`
+	`:mode`
+	`:open`
+	`:s`  with only flags
+	`:t`
+  	`:xit`
+- Some commands, especially those used for flow control, cannot be shortened.
+  E.g., `:throw` cannot be written as `:th`. *E839*
 - You cannot use curly-braces names.
 - A range before a command must be prefixed with a colon: >
 	:%s/this/that
@@ -305,7 +317,7 @@
 
 
 Variable declarations with :var, :final and :const ~
-				*vim9-declaration* *:var*
+				*vim9-declaration* *:var* *E1079*
 				*E1017* *E1020* *E1054* *E1087* *E1108* *E1124*
 Local variables need to be declared with `:var`.  Local constants need to be
 declared with `:final` or `:const`.  We refer to both as "variables" in this
@@ -375,6 +387,9 @@
 without any command.  The same for global, window, tab, buffer and Vim
 variables, because they are not really declared.  Those can also be deleted
 with `:unlet`.
+							*E1065*
+You cannot use `:va` to declare a variable, it must be written with the full
+name `:var`.  Just to make sure it is easy to read.
 							*E1178*
 `:lockvar` does not work on local variables.  Use `:const` and `:final`
 instead.
@@ -952,10 +967,37 @@
 Simple types are Number, Float, Special and Bool.  For other types |string()|
 should be used.
 						*false* *true* *null* *E1034*
-In Vim9 script one can use "true" for v:true, "false" for v:false and "null"
-for v:null.  When converting a boolean to a string "false" and "true" are
-used, not "v:false" and "v:true" like in legacy script.  "v:none" is not
-changed, it is only used in JSON and has no equivalent in other languages.
+In Vim9 script one can use the following predefined values: >
+	true
+	false
+	null
+	null_blob
+	null_channel
+	null_dict
+	null_function
+	null_job
+	null_list
+	null_partial
+	null_string
+`true` is the same as `v:true`, `false` the same as `v:false`, `null` the same
+as `v:null`.
+
+While `null` has the type "special", the other "null_" types have the type
+indicated by their name.  Quite often a null value is handled the same as an
+empty value, but not always.  The values can be useful to clear a script-local
+variable, since they cannot be deleted with `:unlet`.  E.g.: >
+	var theJob = job_start(...)
+	# let the job do its work
+	theJob = null_job
+
+The values can also be useful as the default value for an argument: >
+	def MyFunc(b: blob = null_blob)
+	   if b == null_blob
+	      # b argument was not given
+
+When converting a boolean to a string `false` and `true` are used, not
+`v:false` and `v:true` like in legacy script.  `v:none` has no `none`
+replacement, it has no equivalent in other languages.
 
 Indexing a string with [idx] or taking a slice with [idx : idx] uses character
 indexes instead of byte indexes.  Composing characters are included.