Minor updates.

guide/guide.adoc

@@ -4672,8 +4672,8 @@ Make sure that the instrument is configured to 115,200 baud. Invalid parameters
 passed to the GeoCOM methods will be replaced with their default values, and an
 error message is printed in verbose mode.
 
-If the DMPACK library and module files are installed to `/opt/`, build, link,
-and run the example program with:
+If the DMPACK library and module files are installed to `/opt`, build, link, and
+run the example program with:
 
 ....
 $ gfortran -I/opt/include/dmpack -o geocom geocom.f90 /opt/lib/libdmpack.a -lpcre2-8

src/dm_arg.f90

@@ -17,7 +17,7 @@ module dm_arg
     !!     arg_type('verbose', short='V', type=ARG_TYPE_LOGICAL) &
     !! ]
     !!
-    !! rc = dm_arg_read(args, app='myapp', major=1, minor=0, patch=0)
+    !! rc = dm_arg_read(args)
     !! call dm_error_out(rc)
     !!
     !! call dm_arg_get(args(1), input)
@@ -28,6 +28,9 @@ module dm_arg
     !! Each argument requires name and type. The default type is
     !! `ARG_TYPE_LOGICAL`. The command-line arguments `--help`/-`h` and
     !! `--version`/`-v` are processed automatically by function `dm_arg_read()`.
+    !!
+    !! Additionally, you can pass a callback routine that outputs the version
+    !! string to `dm_arg_read()`.
     use :: dm_ascii
     use :: dm_error
     use :: dm_file