CLDR-18920 Update en_001 BRS item instructions (#4998)

Author: AEApple

docs/site/downloads/brs-copy-en_gb-to-en_001.md

@@ -5,14 +5,19 @@ title: Copy en_GB to en_001
 
 # BRS: Copy en\_GB to en\_001
 
-The program **CompareEn.java** can be used to copy data from en\_GB up to en\_001.
+This task is required to maintain en_001 following the addition of new items or deeper review of existing data.
+Many English locales inherit locale data from [en_001][]
 
-Options:
+The program **CompareEn.java** can be used to copy data from en_GB up to en_001.
 
--   \-u (uplevel) — move elements from en\_GB into en\_oo1. By default, the output directory is common/main and common/annotations in trunk
+### Tool Options
+
+-   \-u (uplevel) — move elements from en_GB into en_001. By default, the output directory is common/main and common/annotations in trunk
     -   If not present, just write a comparison to Generated/cldr/comparison/en.txt
 -   \-v (verbose) — provide verbose output
 
+## Process
+
 1.  Run with no options first.
     1.  That generates a file that indicates what changes would be made.
     2.  Put that file in a spreadsheet
@@ -24,3 +29,23 @@ Options:
     2.  Then do a diff with HEAD to make sure it matches expectations
     3.  Then check in en\_oo1.xml and CompareEn.java
 
+## Review guidelines for inclusion in en_001
+
+World English i.e. en_001 is intended to be as neutral as possible. Only data for items which differ from en need to be upleveled.
+
+This would mean making en_001 have the following characteristics:
+- Date formats
+    - For full, long, medium formats use European style day, month, year. Numeric dates are also day, month, year order where both day and month are zero padded.
+    - en_001 includes a comma following the day name while en_GB does not.
+- Time formats - Use 12 hour clock, as this is the predominant format for English speaking locales ( ref : https://en.wikipedia.org/wiki/Date_and_time_representation_by_country)
+- Spelling of unit names - (metre vs. meter) - Since the BIPM spelling is “metre”, “centimetre”, etc., The “en_001” locale should prefer “metre” over the American spelling “meter”.
+- Compact decimal number formats currently inherit from en until there is evidence that the en_GB abbreviations are the most common globally.
+- For units such as gallon that have both a “US” version and an “imperial” version: Both versions should have the qualifier (“US” or “imperial”), should not remove the “imperial” as in the GB versions.
+- Time zone names: en_001 should use “∅∅∅” to cancel the short metazone names inherited from en since US short metazone names are not relevant for most of the world.
+- Emoji 'names' are determined by the Technical Committee depending on whether the en_GB or en term is more common, while emoji annotation keywords are intended to be a combination of the both locales.
+
+Specific items not in this list may need research to determine common usage.
+
+More about the history of [en_001][]
+
+[en_001]: https://cldr.unicode.org/development/development-process/design-proposals/english-inheritance