UNIQUE constraint

Hi,

I have a question about the UNIQUE constraint.  The documentation
describes this example:

CREATE TABLE example (   a integer,   b integer,   c integer,   UNIQUE (a, c)
);

But it is not clean to me.  Does the above example mean that the list
of pairs must be unique or is it only a short version for this
constraint:

CREATE TABLE example (   a integer UNIQUE,   b integer,   c integer UNIQUE
);

Does the following table fullfill the UNIQUE clause of the example
from the Postgres documentation?
 a b c ----- 1 2 3 1 1 1

cu Sascha

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