Children (of course) and people over 50 are exempt. A Singaporean co-worker from a previous life described it to me thus:
The person to be caned is taken to the roof of a police station where the punishment is administered by a martial arts specialist with a rattan cane soaked overnight in water to make it pliable.
The caning is administered on the backside of their bare trunk whilst they are leaning over a rail for support, with a leather apron used to cover their vital organs in the unlikely case of an errant blow.
The skin is torn on the second or third stroke and a medic present will administer a disinfectant mix of mostly rubbing alcohol between strokes until the court mandated number are administered or the medic determines that the risk of serious damage is too great for further strokes.
While the backside scars are permanent, the ability to crap without pain and walk without a limp returns in about 30 days.
I worked in Kuwait back in the ‘80s and an expat there told me how the Saudis handle caning. Some Brit screwed up and was caught making his own wine. He was sentenced to 100 strokes. The hook was he got 25 at a time - had to show up once a week. Took quite a bit of time to heal. Dunno if it was buttocks or back.