distance between centres of lines；distance between centers of tracks；midway between tracks

distance offset distance

apsidal

apsidal advance

apsidal angle

apsidal axis

apsidal drift

apsidal motion

apsidal period

apsidal surface

apsidal transformation

zero distance connection

2-distance chromatic number

2-distance coloring

3D distance image

3D distance transform

50 Hz industry disturbance

6-minute walking distance test

a long distance monitoring and controlling