Which of the following is true about the WHO analgesic ladder for chronic pain in adults?

The 3 main principles: By the clock: Drugs should be given "around the clock" rather than "on demand". By the mouth: Oral route is preferred. By the ladder: Non-opioids - Mild opioids - Strong opioids. Non opioid analgesic are given for mild pain. Adjuvants can be used for mild, moderate and severe pain