Which root operation is not a modification of anatomy but a nor function performed?

The root operation identified as occlusion is not considered a modification of anatomy; instead, it is a functional action performed on a body part. Occlusion involves deliberately closing off a passage or vessel, leading to a change in the function of that body part rather than its structure.

In the context of ICD-10-PCS, root operations are categorized based on their intent, which can be either a modification of anatomical structure or a performance of a function. Occlusion affects the ability of a vessel or passage to conduct fluids or air, focusing on the functional outcome rather than altering the anatomy itself.

In contrast, operations like transfer and reposition involve changes to anatomical structures, affecting their location or relationship to surrounding tissues. Observation primarily serves to monitor a body part without affecting its anatomy or function, but it's categorized differently from occlusion, which has a direct functional impact.

Thus, occlusion stands out as the only option performed on a body part without modifying anatomical structure, emphasizing its functional characteristic.