[Lowfer] Part 15 Problems.

[KD7JYK DM09]

I recall reading somewhere in Part 15 that a uniquely identifyable signal
must be used.  I know we all follow the rule, but exactly in WHICH section
of Part 15 is this mentioned?

I've been going cross-eyed trying to find it for reference, for example Part
15.xxx.

Any suggestions?

THanks,

Kurt