[erlang-questions] question about erlang doc

[Rustom Mody]

In http://www.erlang.org/doc/man/random.html I see this line:

seed(X1 :: {A1, A2, A3}) -> undefined |
ran()<http://www.erlang.org/doc/man/random.html#type-ran>

Whats the '::' ?
Also I cant figure out how to read what follows the '->'

Please note I am not so much interested in the specifics of random numbers
as in being able to read the manual!
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