Index: TODO
===================================================================
diff -u -r9efc836c8e0eb0106afa5370a3dca6c1bcb7c162 -rd6e5661d520977831094caa5d2c8a5567567ecc3
--- TODO	(.../TODO)	(revision 9efc836c8e0eb0106afa5370a3dca6c1bcb7c162)
+++ TODO	(.../TODO)	(revision d6e5661d520977831094caa5d2c8a5567567ecc3)
@@ -5026,6 +5026,8 @@
 ========================================================================
 TODO:
 
+- remove "-guard" from mixin and filter specs, just have two-element lists?
+
 - why is there no pos/index arg for mixin|filter delete?
 
 - nsf.c: finish forwarder error messages
Index: doc/filter.man.inc
===================================================================
diff -u -rc4cb0af2d70fbb925613e396747d365823be5465 -rd6e5661d520977831094caa5d2c8a5567567ecc3
--- doc/filter.man.inc	(.../filter.man.inc)	(revision c4cb0af2d70fbb925613e396747d365823be5465)
+++ doc/filter.man.inc	(.../filter.man.inc)	(revision d6e5661d520977831094caa5d2c8a5567567ecc3)
@@ -16,9 +16,9 @@
 an existing method of [arg obj] which becomes
 registered as a filter. If having three elements, the third
 element [arg guardExpr] will be stored as a guard expression of the
-[term "filter"]. This guard expression will be evaluated using
-[cmd expr] when [arg obj] receives a message to determine if the
-filter applies. Guard expressions
+[term "filter"]. This guard expression must be a valid Tcl expression
+(see [cmd expr]). [arg expr] is evaluated when [arg obj] receives a message to determine whether the
+filter should intercept the message. Guard expressions
 allow for realizing context-dependent or conditional filter
 composition. If [arg filterSpecList] represents an empty list, any
 existing [term "filter"] will be removed from [arg obj].
@@ -31,12 +31,20 @@
 omitted, [arg index] defaults to the list head (0).
 
 [def "[arg obj] [const [vset SCOPE]] [method {filter delete}] [option -nocomplain] [arg specPattern]"]
-Removes a single [term "filter"] from a current list of [term "filter"]s of
+Removes a single [term "filter"] from the current list of [term "filter"]s of
 [arg obj] whose spec matches [arg specPattern]. [arg specPattern] can
 contain special matching chars (see [cmd "string match"]). [const [vset SCOPE]] [method "filter delete"] will
 throw an error if there is no matching [term "filter"], unless
 [option -nocomplain] is set.
 
+[def "[arg obj] [const [vset SCOPE]] [method {filter guard}] [arg methodName] [arg expr]"]
+
+Registers a guard expression [arg expr] with a filter [arg methodName]
+in a separate step, once the filter was set or added using [const [vset SCOPE]] [method {filter set}] or
+[const [vset SCOPE]] [method {filter add}]. [arg expr] must be a valid Tcl expression (see
+[cmd expr]). An empty string for [arg expr] will clear the currently registered
+guard expression for filter [arg methodName].
+
 [list_end]
 Every [arg methodName] in a [arg spec] must resolve to an existing method in
 the scope of the [vset SCOPE]. To
Index: doc/mixin.man.inc
===================================================================
diff -u -rc4cb0af2d70fbb925613e396747d365823be5465 -rd6e5661d520977831094caa5d2c8a5567567ecc3
--- doc/mixin.man.inc	(.../mixin.man.inc)	(revision c4cb0af2d70fbb925613e396747d365823be5465)
+++ doc/mixin.man.inc	(.../mixin.man.inc)	(revision d6e5661d520977831094caa5d2c8a5567567ecc3)
@@ -31,6 +31,14 @@
 [comment {Therefore, by default, any added [term "mixin class"] takes precedence over previously added classes in the overall linearisation of [arg obj].}]
 [def "[arg obj] [const [vset SCOPE]] [method {mixin delete}] [option -nocomplain] [arg specPattern]"]
 Removes a [term "mixin class"] from a current list of [term "mixin class"]es of [arg obj] whose spec matches [arg specPattern]. [arg specPattern] can contain special matching chars (see [cmd "string match"]). [const [vset SCOPE]] [method "mixin delete"] will throw an error if there is no matching [term "mixin class"], unless [option -nocomplain] is set.
+
+[def "[arg obj] [const [vset SCOPE]] [method {mixin guard}] [arg className] [arg expr]"]
+
+Registers a guard expression [arg expr] with the [term "mixin class"] [arg className]
+in a separate step, once the [term "mixin class"] was set or added using [const [vset SCOPE]] [method {mixin set}] or
+[const [vset SCOPE]] [method {mixin add}]. [arg expr] must be a valid Tcl expression (see
+[cmd expr]). An empty string for [arg expr] will clear the currently registered
+guard expression for the registered [term "mixin class"] [arg className].
 [list_end]
 [comment {
   A [term "mixin class"] whose spec is featured earlier in [arg mixinSpecList] takes