Photoshop Transfer Function
Photoshop Transfer Function is a Photoshop format that stores a transfer function, i.e. a way to adjust the brightness, contrast, etc. of an image.
It is distinct from Photoshop Curve format, though the formats appear to be used for roughly the same purposes.
According to the documentation, a Transfer Function file begins with bytes
00 04, and is exactly 114 bytes in size.