Refer to figure.
ICAO Annex 14 - Volume I
5.3.8 Runway threshold identification lights

5.3.8.2 Runway threshold identification lights shall be located symmetrically about the runway centre line, in line with the threshold and approximately 10 m outside each line of runway edge lights.

5.3.8.3 Recommendation.— Runway threshold identification lights should be flashing white lights with a flash frequency between 60 and 120 per minute.

• Runway edge lights → fixed lights showing variable white.
• Runway threshold identification lights → flashing white lights.
• Runway centerline lights → fixed lights showing variable white from the threshold to the point 900 m from the runway end; alternate red and variable white from 900 m to 300 m from the runway end; and red from 300 m to the runway end, except that for runways less than 1800 m in length, the alternate red and variable white lights shall extend from the midpoint of the runway usable for landing to 300 m from the runway end.
• Crossbar lights → fixed lights showing variable white.