runtime(doc): clarify syntax vs matching mechanism

fixes: #14643

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/builtin.txt

@@ -9980,6 +9980,10 @@ synconcealed({lnum}, {col})				*synconcealed()*
 			synconcealed(lnum, 5)   [1, 'X', 2]
 			synconcealed(lnum, 6)   [0, '', 0]
 
+		Note: Doesn't consider |matchadd()| highlighting items,
+		since syntax and matching highlighting are two different
+		mechanisms |syntax-vs-match|.
+
 
 synstack({lnum}, {col})					*synstack()*
 		Return a |List|, which is the stack of syntax items at the

runtime/doc/pattern.txt

@@ -1,4 +1,4 @@
-*pattern.txt*   For Vim version 9.1.  Last change: 2023 Oct 23
+*pattern.txt*   For Vim version 9.1.  Last change: 2024 Apr 26
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1394,6 +1394,19 @@ Finally, these constructs are unique to Perl:
 ==============================================================================
 10. Highlighting matches				*match-highlight*
 
+							*syntax-vs-match*
+		Note that the match highlight mechanism is independent
+		of |syntax-highlighting|, which is (usually) a buffer-local
+		highlighting, while matching is window-local, both methods
+		can be freely mixed.  Match highlighting functions give you
+		a bit more flexibility in when and how to apply, but are
+		typically only used for temporary highlighting, without strict
+		rules.  Both methods can be used to conceal text.
+
+		Thus the matching functions like |matchadd()| won't consider
+		syntax rules and functions like |synconcealend()| and the
+		other way around.
+
 							*:mat* *:match*
 :mat[ch] {group} /{pattern}/
 		Define a pattern to highlight in the current window.  It will

runtime/doc/syntax.txt

@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2024 Apr 22
+*syntax.txt*	For Vim version 9.1.  Last change: 2024 Apr 26
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -4314,7 +4314,9 @@ Whether or not it is actually concealed depends on the value of the
 'conceallevel' option.  The 'concealcursor' option is used to decide whether
 concealable items in the current line are displayed unconcealed to be able to
 edit the line.
-Another way to conceal text is with |matchadd()|.
+
+Another way to conceal text is with |matchadd()|, but internally this works a
+bit differently |syntax-vs-match|.
 
 concealends						*:syn-concealends*
 
@@ -4322,7 +4324,9 @@ When the "concealends" argument is given, the start and end matches of
 the region, but not the contents of the region, are marked as concealable.
 Whether or not they are actually concealed depends on the setting on the
 'conceallevel' option. The ends of a region can only be concealed separately
-in this way when they have their own highlighting via "matchgroup"
+in this way when they have their own highlighting via "matchgroup".  The
+|synconcealed()| function can be used to retrieve information about conealed
+items.
 
 cchar							*:syn-cchar*
 							*E844*

runtime/doc/tags

@@ -10186,6 +10186,7 @@ syntax-latex	syntax.txt	/*syntax-latex*
 syntax-loading	syntax.txt	/*syntax-loading*
 syntax-printing	usr_06.txt	/*syntax-printing*
 syntax-tex	syntax.txt	/*syntax-tex*
+syntax-vs-match	pattern.txt	/*syntax-vs-match*
 syntax.txt	syntax.txt	/*syntax.txt*
 syntax_cmd	syntax.txt	/*syntax_cmd*
 sys-file-list	help.txt	/*sys-file-list*

runtime/doc/usr_41.txt

@@ -1,4 +1,4 @@
-*usr_41.txt*	For Vim version 9.1.  Last change: 2024 Feb 25
+*usr_41.txt*	For Vim version 9.1.  Last change: 2024 Apr 26
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -1096,7 +1096,7 @@ Syntax and highlighting:	  *syntax-functions* *highlighting-functions*
 	synIDattr()		get a specific attribute of a syntax ID
 	synIDtrans()		get translated syntax ID
 	synstack()		get list of syntax IDs at a specific position
-	synconcealed()		get info about concealing
+	synconcealed()		get info about (synax) concealing
 	diff_hlID()		get highlight ID for diff mode at a position
 	matchadd()		define a pattern to highlight (a "match")
 	matchaddpos()		define a list of positions to highlight