Any idea why public function like "svn_fspath__dirname" have double "__" in its name?

[Kamesh Jayachandran]

Hi All,

I could see the following functions in our public header with '__' in 
their names,

svn_fspath__is_canonical
svn_fspath__dirname
svn_fspath__basename
svn_fspath__split
svn_fspath__join
svn_fspath__is_child
svn_fspath__skip_ancestor
svn_fspath__is_ancestor
svn_fspath__get_longest_ancestor
svn_error__locate

svn_error__malfunction

IIUC "__" convention is used for semi-public functions where we may not 
keep BC promise.

Do I miss something?

With regards
Kamesh Jayachandran