A Presidential News Conference was officially open when the President simply said 'Helen'.

A Presidential News Conference was officially over when Helen said 'Thank You, Mr. President'.

That 'Helen' was Helen Thomas, the so called 'Dean' of the White House Press corps.

Helen Thomas has passed away at the age of 92.

For decades Thomas worked for United Press International, beginning with the first President she covered, John F. Kennedy.  Since then Helen knew and quizzed (some would say badgered) them all.

Johnson.  Nixon.  Ford.  Carter.  Reagan.  Bush.  Clinton.  Bush.  Obama.

She would ask the first question of every White House Press Conference from her perch in the front row.  And when she said 'Thank You Mr. President', that signaled the conference was over.