Final answer:
Secondary diagnosis codes represent the secondary condition present alongside the primary disease, helping healthcare providers track and document the patient's full medical condition.
Step-by-step explanation:
The codes that represent the secondary condition that is present in addition to the underlying or primary disease are called secondary diagnosis codes. These codes provide information about the secondary condition and help healthcare providers track and document the full extent of a patient's medical condition. For example, if a patient has diabetes (primary condition) and also develops a foot ulcer (secondary condition), the secondary diagnosis code would indicate the presence of the foot ulcer.