(written from a Production point of view)
Jef Duncan 21st century was a male Human mentioned on a medical file prepared for the Star Trek: Enterprise third season episode "Carpenter Street". While a number of forms different were seen on screen, none of them were readable or even especially recognizable, so it remains unclear if the information about Duncan was seen in the episode.
According to this form, he was born in Rhode, Michigan on November 27, 1944. He was examined by medical staff at UCLA and lived at 4570 1st Street in Detroit. On October 6, 2004, Duncan was a blood donor at the Porter Street blood bank in Detroit, Michigan.
The form can be seen at YourProps.com.