Da Jian (11.01) and Xiao Jian (11.02) are also called Big Distance and Small Distance. These two points are basically located on the Large Intestine channel (though not directly on the line between LI 1 and LI 1 and have a strong connection with the Liver channel.
Both of these points are located on the B-line of the 2nd (index) finger on the proximal interphalangeal bone.
Da Jian is located 1/2 way between the MCP joint and the PIP joint.
Xiao Jian is located 1/2 way between Da Jian and the PIP joint. You could also say Xiao Jian is located 1/4 of the distanced as measured from the PIP joint to the MCP joint.