These break out to:
Elementary: 1/1/08 and younger (1st year novice and below)
Middle school: 12/31/07 to 9/1/04 (2nd year novice, schoolgirl, some cadets).
High School:2000-2004 (cadet and junior)
There is overlap in the middle school and high school age groups.
I personally hate this type of grouping as it conflates age and grade.
I have seen the "hs" category used repeatedly at regionals- boys have cadet (age based) but it is highly confusing/ potentially leaves out 8th grade cadet girls when they only available category is "high school".