According to the Huffington Post, "full code" is a hospital designation that means to intercede if a patient's heart stops beating or if the patient stops breathing. It is the opposite code of DNR/DNI, meaning "Do Not Resuscitate/Do Not Intubate."
When a patient enters a hospital, she is automatically coded under full code unless she or her family requests otherwise, notes the Huffington Post. Being designated under full code gives the hospital the authority to try to bring the patient back from a near-death situation. Patients can choose to allow only certain treatments in a emergency, such as intubation only but not resuscitation.