Easton's Bible Dictionary (1897)
The border of blood = Ephes-dammim (q.v.), between Shochoh and Azekah (1 Sam. 17:1; 1 Chr. 11:13).
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
PAS-DAM'MIM (boundary of blood), the scene of fierce contests between the Israelites and the Philistines. 1 Chr 11:13. It is called Ephes-dammim in 1 Sam 17:1. It was on the side of the valley of Elah, and Van de Velde proposes to identify it with the ruins called Damum, 3 miles east of Shochoh, about 11 miles south-west of Jerusalem.