What are the R sorting rules of character vectors?

Question

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 not 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?

Answer 1

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.