X-apple-i-md-m
Unpacking the Mystery: What is x-apple-i-md-m?
I began to experiment. I wrote a script to reply to the header with a custom value: x-apple-i-md-m: acknowledge . The fan spun up. The screen flickered—not off, but sideways , as if the display was trying to show me a reflection of a room I wasn't in. My coffee mug was on the left in reality. In the reflection, it was on the right.
From a privacy standpoint, Apple treats this data as internal telemetry. They do not share it with app developers. But for privacy extremists, it confirms that Apple does maintain a persistent hardware identifier beyond the Advertising Identifier (IDFA). x-apple-i-md-m
X-APPLE-I-MD-M.
