* io.c (IO#new):

Documentation for IO#open modes and formatting
  [ruby-core#48052] [Bug #7179]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37443 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

io.c

@@ -6962,31 +6962,32 @@ rb_io_stdio_file(rb_io_t *fptr)
  *
  *  Ruby allows the following open modes:
  *
- *  "r"  :: Read-only, starts at beginning of file  (default mode).
+ *	"r"  Read-only, starts at beginning of file  (default mode).
  *
- *  "r+" :: Read-write, starts at beginning of file.
+ *  	"r+" Read-write, starts at beginning of file.
  *
- *  "w"  :: Write-only, truncates existing file
+ *  	"w"  Write-only, truncates existing file
  *  	     to zero length or creates a new file for writing.
  *
- *  "w+" :: Read-write, truncates existing file to zero length
+ *  	"w+" Read-write, truncates existing file to zero length
  *  	     or creates a new file for reading and writing.
  *
- *  "a"  :: Write-only, starts at end of file if file exists,
+ *  	"a"  Write-only, starts at end of file if file exists,
  *  	     otherwise creates a new file for writing.
  *
- *  "a+" :: Read-write, starts at end of file if file exists,
+ *  	"a+" Read-write, starts at end of file if file exists,
  *	     otherwise creates a new file for reading and
  *  	     writing.
  *
- *  "b"  :: Binary file mode (may appear with
- *          any of the key letters listed above).
+ *  The following modes must be used separately, and along with one or more of
+ *  the modes seen above.
+ *
+ *	"b"  Binary file mode
  *  	     Suppresses EOL <-> CRLF conversion on Windows. And
  *  	     sets external encoding to ASCII-8BIT unless explicitly
  *  	     specified.
  *
- *  "t"  :: Text file mode (may appear with
- *          any of the key letters listed above except "b").
+ *  	"t"  Text file mode
  *
  *  When the open mode of original IO is read only, the mode cannot be
  *  changed to be writable.  Similarly, the open mode cannot be changed from