diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 057d201..baf3693 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.0.  Last change: 2023 Apr 24
+*syntax.txt*	For Vim version 9.0.  Last change: 2023 Dec 05
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -1591,7 +1591,15 @@
 Default highlighting and dialect ~
 Highlighting appropriate for Fortran 2008 is used by default.  This choice
 should be appropriate for most users most of the time because Fortran 2008 is
-almost a superset of previous versions (Fortran 2003, 95, 90, and 77).
+almost a superset of previous versions (Fortran 2003, 95, 90, and 77).  A
+small number of features new to Fortran 2018 and Fortran 2023 are supported
+and the complete transition to Fortran 2023 will be completed in the future.
+A few legacy constructs deleted or declared obsolescent in recent Fortran
+standards are highlighted as todo items.
+
+The syntax script no longer supports Fortran dialects.  The variable
+fortran_dialect is now silently ignored.  Since computers are much faster now,
+the variable fortran_more_precise is no longer needed and is silently ignored.
 
 Fortran source code form ~
 Fortran code can be in either fixed or free source form.  Note that the
@@ -1618,14 +1626,36 @@
 determine which source form has been used by examining the file extension
 using conventions common to the ifort, gfortran, Cray, NAG, and PathScale
 compilers (.f, .for, .f77 for fixed-source, .f90, .f95, .f03, .f08 for
-free-source). If none of this works, then the script examines the first five
-columns of the first 500 lines of your file.  If no signs of free source form
-are detected, then the file is assumed to be in fixed source form.  The
-algorithm should work in the vast majority of cases.  In some cases, such as a
-file that begins with 500 or more full-line comments, the script may
-incorrectly decide that the fortran code is in fixed form.  If that happens,
-just add a non-comment statement beginning anywhere in the first five columns
-of the first twenty-five lines, save (:w) and then reload (:e!) the file.
+free-source). No default is used for the .fpp and .ftn file extensions because
+different compilers treat them differently. If none of this works, then the
+script examines the first five columns of the first 500 lines of your file. If
+no signs of free source form are detected, then the file is assumed to be in
+fixed source form.  The algorithm should work in the vast majority of cases.
+In some cases, such as a file that begins with 500 or more full-line comments,
+the script may incorrectly decide that the code is in fixed form.  If that
+happens, just add a non-comment statement beginning anywhere in the first five
+columns of the first twenty-five lines, save (:w), and then reload (:e!) the
+file.
+
+Vendor extensions ~
+Fixed-form Fortran requires a maximum line length of 72 characters but the
+script allows a maximum line length of 80 characters as do all compilers
+created in the last three decades.  An even longer line length of 132
+characters is allowed if you set the variable fortran_extended_line_length
+with a command such as >
+    :let fortran_line_length=1
+placed prior to the :syntax on command.
+
+If you want additional highlighting of the CUDA Fortran extensions, you should
+set the variable fortran_CUDA with a command such as >
+    :let fortran_CUDA=1
+placed prior to the :syntax on command.
+
+To activate recognition of some common, non-standard, vendor-supplied
+intrinsics, you should set the variable fortran_vendor_intrinsics with a
+command such as >
+    :let fortran_vendor_intrinsics=1
+placed prior to the :syntax on command.
 
 Tabs in fortran files ~
 Tabs are not recognized by the Fortran standards.  Tabs are not a good idea in
@@ -1647,8 +1677,8 @@
 also set the variable fortran_fold_conditionals with a command such as >
     :let fortran_fold_conditionals=1
 then fold regions will also be defined for do loops, if blocks, and select
-case constructs.  If you also set the variable
-fortran_fold_multilinecomments with a command such as >
+case constructs.  If you also set the variable fortran_fold_multilinecomments
+with a command such as >
     :let fortran_fold_multilinecomments=1
 then fold regions will also be defined for three or more consecutive comment
 lines.  Note that defining fold regions can be slow for large files.
@@ -1659,58 +1689,6 @@
 units are not folded because they are seen as not belonging to any program
 unit.
 
-More precise fortran syntax ~
-If you set the variable fortran_more_precise with a command such as >
-    :let fortran_more_precise=1
-then the syntax coloring will be more precise but slower.  In particular,
-statement labels used in do, goto and arithmetic if statements will be
-recognized, as will construct names at the end of a do, if, select or forall
-construct.
-
-Non-default fortran dialects ~
-The syntax script supports two Fortran dialects: f08 and F. You will probably
-find the default highlighting (f08) satisfactory.  A few legacy constructs
-deleted or declared obsolescent in the 2008 standard are highlighted as todo
-items.
-
-If you use F, the advantage of setting the dialect appropriately is that
-other legacy features excluded from F will be highlighted as todo items and
-that free source form will be assumed.
-
-The dialect can be selected in various ways.  If all your fortran files use
-the same dialect, set the global variable fortran_dialect in your .vimrc prior
-to your syntax on statement.  The case-sensitive, permissible values of
-fortran_dialect are "f08" or "F".  Invalid values of fortran_dialect are
-ignored.
-
-If the dialect depends upon the file extension, then it is most convenient to
-set a buffer-local variable in a ftplugin file.  For more information on
-ftplugin files, see |ftplugin|.  For example, if all your fortran files with
-an .f90 extension are written in the F subset, your ftplugin file should
-contain the code >
-    let s:extfname = expand("%:e")
-    if s:extfname ==? "f90"
-	let b:fortran_dialect="F"
-    else
-	unlet! b:fortran_dialect
-    endif
-Note that this will work only if the "filetype plugin indent on" command
-precedes the "syntax on" command in your .vimrc file.
-
-Finer control is necessary if the file extension does not uniquely identify
-the dialect.  You can override the default dialect, on a file-by-file basis,
-by including a comment with the directive "fortran_dialect=xx" (where xx=F or
-f08) in one of the first three lines in your file.  For example, your older .f
-files may be legacy code but your newer ones may be F codes, and you would
-identify the latter by including in the first three lines of those files a
-Fortran comment of the form >
-  ! fortran_dialect=F
-
-For previous versions of the syntax, you may have set fortran_dialect to the
-now-obsolete values "f77", "f90", "f95", or "elf". Such settings will be
-silently handled as "f08". Users of "elf" may wish to experiment with "F"
-instead.
-
 The syntax/fortran.vim script contains embedded comments that tell you how to
 comment and/or uncomment some lines to (a) activate recognition of some
 non-standard, vendor-supplied intrinsics and (b) to prevent features deleted