What constitutes being "old school" in the military?

Old School is going to Basic with an M-1 or M-14, whatinnahell are PT Shorts? We did PT in cotton fatigues and steel pots. Yep duce and half, M-16, never got one until my SECOND tour in Viet Nam, ate C-Rats, not this MRE stuff, lived in wooden barracks, chant 'Kill A Commie for Mommie' during PT and marches, some at double time, full gear, boots and doggie straps. Half of a shelter half, sent my fatigues out for starch from hell, could stand them up in the corner before 'breaking starch' spit shined boots and low quarters.
That is what an old timer did, at least I did... hahaha

Old school is what you lived and experienced. Hopefully you can pass some wisdom on to a knucklehead like you were.

My old man is the company commander in front. Old school. He was a Private in WW1.

Whenever something changes that the person saying it perceives as significant. I initially joined in 2000 and had 3 separate periods of service during that time until I got medically retired at 15 years active. The things people said made them old school were hilarious and honestly it's all just arbitrarily made up. One person's old school is another person's "soft new Army".

I was in the USMC prior to the Army, I was issued an M14 (better weapon), prior to the Mighty Mattel M16 (piece of crap). We humped everywhere, no trucks, buses for us. Wore the game “pickle uniform” and it and the cover (cap) were starched.

You had to have white underwear, just for them to be light blue after wearing your Navy dungarees for a couple hours in Orlando's summer.

Wearing the stiff (plank) Navy dungarees for water survival. Trying to fill them with air

Eating cough drops for candy during boot camp. No contraband allow.

Camouflage was for Army, Marines, and special forces.

It was mandatory to get you hair cut for boot camp by a boot camp barber.

Seeing rabbits around Orlando's Navy base except when they're serving fried chicken.

Cussing and no such things as personal boundaries

Walking on the grass was like walking on water. Not possible

Hell week!

Well, when I enlisted in 1956, we were issued brown low-quarter shoes and brown combat boots, both of which we had to dye black while still in basic training. Uniforms were WW II OD Ike Jackets and rifles were M-1 Garands. That should qualify me as being "old school".

At this point I would say understanding rank structure and where you fall in it.

Ur old school if u pulled fire watch in ur old school WWII barracks that had bullet holes still embedded from the jap zeros that bombed Pearl ….

Cigarettes in C-rations!