The question of whether everyone sees seven colours in a rainbow is related to the idea of linguistic relativity. […] recent research suggests that the number of distinct colours observed and what these are called depend on the language that one uses, with people whose language has fewer colour words seeing fewer discrete colour bands.
Two date formats are commonly used in Wikipedia articles: December 2, 2009 and 2 December 2009. These are referred to as alphanumeric dates. The first is used in articles with a connection to the United States, and the second in articles relating to most Commonwealth countries (although no preference is expressed for Canada). In articles with no particular national affiliation, to prevent needless edit warring, the established date format should not be changed. However any given article should use just one of the two formats consistently. Dates that are all numeric are highly discouraged to avoid confusion, however if used must be in the YYYY-MM-DD format and never in YYYY-DD-MM format.
