This script marks important seasonal dates with a vertical line that Gann used to watch for Trend changes.
March 21st
June 22nd
September 23rd
December 22nd
And 50% Levels - Minor seasonal dates.
February 4th
May 6th
August 8th
November 7th
In the settings you can change line colors and toggle the Offset. Offset is the way the script draws lines to show future dates, I offset by 365 so it will show incorrectly at some points in back testing.