datum line [测] 基准线 ; 基准面 ; 基线 ; 坐标线
datum line differential [机] 基准线差
Y-datum line Y 基准线
datum line beam 基准梁
armament datum line 军械基准线 ; 武器基准线
the datum line of sunlight 日照基准线
central datum line 中心基准线
sunlight datum line 日照基准线
Perpendicularity - is the condition of a surface, axis, or line, which is 90 deg. From a datum plane or a datum axis.
垂直度-条件是表面，轴，或线，这是90度的基准平面或基准轴。
The precondition of RG line being as datum of time-depth conversion is that the RG line is equivalent to the smooth line of surface elevation.
RG线作为时深转换基准面的前提是RG线等效于地表高程的平滑线。
This paper also presents a method to solve the tunnel axis displacement on line caused by angle error between tube center axis and datum of joint.
分析了对接面与管段中心线夹角误差对沉放后线路位置的影响，提出了控制隧道轴线偏差的措施；
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