基線 is read as きせん (kisen) and means base line.
きせん
kisen
きじゅんせん
reference line
かいはつきほんせん
developmental baseline
もじきじゅんせん
character base line
ぜんせんきち
frontline (military) base
きじゅん
standard
もと
cause
きほん
basics
きち
base (military, expedition, etc.)
きばん
bedrock
きそ
foundation
もとづく
to be based (on)
きほんてき
fundamental