There is another thread on this over on advocacy and safety: http://www.bikeforums.net/showthread.php?t=194610

As noted in that thread, I carry a laminated business card with my home contact info on the back. At least back in the day when I was doing the paramedic thing, we didn't routinely check for hidden dog tags. Perhaps the state of the art is different now. I will say, however, that for a female patient, I would only check in the presence of my partner or if the patient was conscious. And if they are conscious and alert, you can just ask them. I can see where unzipping the jersey or fishing around in the sports bra of a female rider, without an obvious clinical reason, such as an injury to the torso, could easily be miscontrued by the patient or onlookers, and could lead to 'inappropriate contact' complaints and disciplinary action. Although this may sound ridiculous to some, it is the sort of thing that healthcare providers have to be cautious about.

My other comments in terms of notification, etc. can be found in the other thread.