IMHO There are some misprints both in documentation and in source of
a) In the documentation of the function FcUtf8ToUcs4
(http://fontconfig.org/fontconfig-devel/r3058.html) there should be
"must" instead of "nust" in this part of the text "src nust be at least
len bytes long."
b) IMHO the name of those two functions should be
FcConfigSetRescanInterval and FcConfigGetRescanInterval instead of
FcConfigSetRescanInverval and FcConfigGetRescanInverval. There is "v"
instead of "t" in the word Inverval (should be Interval). This misprint
is in both the documentation as the source of the library.