used for some languages where the words use
  only ASCII letters for most of the words.

The default "spellfile.vim" plugin uses this autocommand, if you define your
autocommand afterwards you may want to use ":au! SpellFileMissing" to overrule
it.  If you define your autocommand before the plugin is loaded it will notice
this and not do anything.
							*E797*
Note that the SpellFileMissing autocommand must not change or destroy the
buffer the user was editing.

==============================================================================
4. Spell file format					*spell-file-format*

This is the format of the files that are used by the person who creates and
maintains a word list.

Note that we avoid the word "dictionary" here.  That is because the goal of
spell checking differs from writing a dictionary (as in the book).  For
spelling we need a list of words that are OK, thus should not be highlighted.
Person and company names will not appear in a dictionary, but do appear in a
word list.  And some old words are rarely used while they are common
misspellings.  These do appear in a dictionary but not in a word list.

There are two formats: A straight list of words and a list using affix
compression.  The files with affix compression are used by Myspell (Mozilla
and OpenOffice.org).  This requires two files, one with .aff and one with .dic
extension.


FORMAT OF STRAIGHT WORD LIST				*spell-wordlist-format*

The words must appear one per line.  That is all that is required.

Additionally the following items are recognized:

- Empty and blank lines are ignored.

	# comment ~
- Lines starting with a # are ignored (comment lines).

	/encoding=utf-8 ~
- A line starting with "/encoding=", before any word, specifies the encoding
  of the file.  After the second '=' comes an encoding name.  This tells Vim
  to setup conversion from the specified encoding to 'encoding'.  Thus you can
  use one word list for several target encodings.

	/regions=usca ~
- A line starting with "/regions=" specifies the region names that are
  supported.  Each region name must be two ASCII letters.  The first one is
  region 1.  Thus "/regions=usca" has region 1 "us" and region 2 "ca".
  In an addition word list the region names should be equal to the main word
  list!

- Other lines starting with '/' are reserved for future use.  The ones that
  are not recognized are ignored.  You do get a warning message, so that you
  know something won't work.

- A "/" may follow the word with the following items:
    =		Case must match exactly.
    ?		Rare word.
    !		Bad (wrong) word.
    1 to 9	A region in which the word is valid.  If no regions are
		specified the word is valid in all regions.

Example:

	# This is an example word list		comment
	/encoding=latin1			encoding of the file
	/regions=uscagb				regions "us", "ca" and "gb"
	example					word for all regions
	blah/12					word for regions "us" and "ca"
	vim/!					bad word
	Campbell/?3				rare word in region 3 "gb"
	's mornings/=				keep-case word

Note that when "/=" is used the same word with all upper-case letters is not
accepted.  This is different from a word with mixed case that is automatically
marked as keep-case, those words may appear in all upper-case letters.


FORMAT WITH .AFF AND .DIC FILES				*aff-dic-format*

There are two files: the basic word list and an affix file.  The affix file
specifies settings for the language and can contain affixes.  The affixes are
used to modify the basic words to get the full word list.  This significantly
reduces the number of words, especially for a language like Polish.  This is
called affix compression.

The basic word list and the affix file are combined with the ":mkspell"
command and results in a binary spell file.  All the preprocessing has been
done, thus this file loads fast.  The binary spell file format is described in
the source code (src/spell.c).  But only developers need to know about it.

The preprocessing also allows us to take the Myspell language