Objective CAML's sum types are discriminated unions. Refer to chapter 2, page ?? for a full description.
Linking is performed differently for the bytecode compiler and the native-code compiler.
Recall that a function such as fst, of type 'a * 'b -> 'a, does not have two arguments, but only one that happens to be a pair; on the other hand, a function of type int -> int -> int has two arguments.
Under Unix, this directory is /usr/local/lib/ocaml by default, or sometimes /usr/lib/ocaml. Under Windows, the default location is C:\OCAML\LIB, or the value of the environment variable CAMLLIB, if set.
More precisely, by their ISO Latin-1 code, which is an 8-bit character encoding extending ASCII with accented letters and signs for Western languages. Objective CAML does not yet handle wider internationalized character sets such as Unicode.
Here, the tag bit is the least significant bit.