What are the differences between the Canadian ispell dictionaries

On my Ubuntu 20.04 system, I seem to have five different Canadian English dictionaries installed for ispell:

• en_CA
• en_CA-variant_0
• en_CA-variant_1
• en_CA-w_accents
• en_CA-wo_accents

I have searched the ispell project website for information on the differences between them. I have checked for any discussions on stackexchange. But so far I have not found any information.

What are the differences between them all?

The Aspell project is designed to be a replacement for ispell and uses the same English dictionaries (probably uses the same dictionaries for other languages too). I downloaded the latest version of the English dictionaries aspell6-en-2020.12.07-0.tar.bz2 and it contains a file called extra.txt which explains the different dictionaries. Summarizing the file:

• en_CA = en_CA-wo_accents. This dictionary has one "most accepted" spelling of every word. It does not include accents, in other words é, è, and all other accented 'e's appear simply as 'e'
• en_CA-w_accents is the same as above but includes the relevant accents on each letter
• en_CA-variant_0 includes multiple spellings of some words when those spellings are equally accepted in Canadian English. It is a superset of en_CA
• en_CA-variant_1 includes more multiple spellings that are less standard. It is a superset of en_CA-variant_0

For those interested in the whole explanation:

 INFORMATION ON THE PROVIDED DICTIONARIES

This word list package supports the following dialects of English:

  American (en_US)
  British with "ise" spelling (en_GB-ise)
  British with "ize" spelling (en_GB-ize)
  Canadian (en_CA)

In addition generic English (en) is supported which is a combination
of all the above.

For each dialect there is the option to either strip accents (for
example cafe) or keep them (for example café).  The default is to
strip them.

Combining these two options gives the following dictionaries.  

  en_US-wo_accents
  en_US-w_accents
  en_GB-ise-wo_accents
  en_GB-ise-w_accents
  en_GB-ize-wo_accents
  en_GB-ize-w_accents
  en_CA-wo_accents
  en_CA-w_accents
  en-wo_accents
  en-w_accents

in addition to the following aliases:

  en_US = en_US-wo_accents
  en_GB = en_GB-ise-wo_accents
  en_GB-ise = en_GB-ise-wo_accents
  en_GB-ize = en_GB-ize-wo_accents
  en_GB-wo_accents = en_GB-ise-wo_accents
  en_GB-w_accents = en_GB-ize-w_accents
  en_CA = en_CA-wo_accents
  en = en-wo_accents

  american-* = en_US-*
  britsh-* = en_GB-*
  canadian-* = en_CA-*
  english-* = en-*

If you are using Aspell 0.60 these aliases can be changed locally via
"dict-alias" option.  For example if you prefer the "ize" spelling for
British English add the line:

  add-dict-alias en_GB en_GB-ize

to ".aspell.conf".

Great care has been taken so that that, for the most part, only one
spelling for any particular word is included in the main dictionary.
When two variants were considered equal I randomly picked one for
inclusion in the main word list.  Unfortunately this means that my
choice in how to spell a word may not match your choice.  For this
reason the following auxiliary dictionaries are provided:

  en_US-variant_0
  en_US-variant_1
  en_GB-variant_0
  en_GB-variant_1
  en_CA-variant_0
  en_CA-variant_1
  en-variant_2

These dictionaries are meant to be used in addition to one of the
standard dictionaries. To specify them use the "extra-dicts" option.
The "en_*-variant_0" dictionaries includes most variants which are
considered almost equal, "variant_1" includes variants which are
generally considered acceptable, and "variant_2" contains variants
which are seldom used and may not even be considered correct.  It is
only necessary to use on of these dictionaries since, for example,
"en_US-variant_1" includes all the words in "en_US-variant_0".


UPGRADING FROM ASPELL6-EN-0.01

If you are upgrading from the aspell6-en-0.01 package you should do a

  rm `aspell config dict-dir`/en[-_]*.alias

to remove any old alias.  Otherwise aspell may get confused as this
version installs the alias with the ".multi" extension instead of
the ".alias" extension.