What are the R sorting rules of character vectors?

R sorts character vectors in a sequence which I describe as alphabetic, not ASCII.

For example:

sort(c("dog", "Cat", "Dog", "cat"))
[1] "cat" "Cat" "dog" "Dog"

Three questions:

1. What is the technically correct terminology to describe this sort order?
2. I can 开发者_StackOverflownot find any reference to this in the manuals on CRAN. Where can I find a description of the sorting rules in R?
3. is this any different from this sort of behaviour in other languages like C, Java, Perl or PHP?

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Details: for sort() states:

 The sort order for character vectors will depend on the collating
 sequence of the locale in use: see ‘Comparison’.  The sort order
 for factors is the order of their levels (which is particularly
 appropriate for ordered factors).

and help(Comparison) then shows:

 Comparison of strings in character vectors is lexicographicwithin
 the strings using the collating sequence of the locale in use:see
 ‘locales’.  The collating sequence of locales such as ‘en_US’ is
 normally different from ‘C’ (which should use ASCII) and can be
 surprising.  Beware of making _any_ assumptions about the 
 collation order: e.g. in Estonian ‘Z’ comes between ‘S’ and ‘T’,
 and collation is not necessarily character-by-character - in
 Danish ‘aa’ sorts as a single letter, after ‘z’.  In Welsh ‘ng’
 may or may not be a single sorting unit: if it is it follows ‘g’.
 Some platforms may not respect the locale and always sort in
 numerical order of the bytes in an 8-bit locale, or in Unicode
 point order for a UTF-8 locale (and may not sort in the same order
 for the same language in different character sets).  Collation of
 non-letters (spaces, punctuation signs, hyphens, fractions and so
 on) is even more problematic.

so it depends on your locale setting.

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Sorting depends on locale. My solution for that is the following...

I create ~/.Renviron file

cat ~/.Renviron 
#LC_ALL=C

then in R sorting is in C locale

x=c("A", "B", "d", "F", "g", "H")
sort(x)
#[1] "A" "B" "F" "H" "d" "g"