What do those flags mean?????

GREEN: The race is underway when the green flag is waved.
YELLOW: Take care, DANGER. No passing on entire course. Drivers to form a
single line and close up with the leader, and follow the Starter's
directions.
single line and close up with the leader, and follow the Starter's
directions.

YELLOW AND WHITE: These two flags drawn together by the starter
are to indicate that the field is not sufficiently
bunched for the restart.
are to indicate that the field is not sufficiently
bunched for the restart.

WHITE: One lap to go.

WHITE Crossed with GREEN FLAG means half way point.