To read a map, take note of the compass direction, the legend, and the reference lines.

为了读懂地图，要注意指南针方向、图例以及基准线。

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Direction, especially angular direction measured from one position to another using geographical or celestial reference lines.

方位，相对位置：方向，尤指用地理学的或天体图线测量的从一个固定位置到另一个位置的带有角度的方向。

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Note: to reference the lines of assembly code in the following explanation, I refer to the last two values of the instruction address because they all begin with 054d20.

注：为引用下列说明中的汇编代码行，我将引用指令地址的最后两个值，因为它们都以054d 20开头。

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Then Ecosign sends foresters and surveyors equipped with GPS, topographical maps and compasses to the slopes to scramble the steep trails, marking central reference lines with flagging tape, determining boundaries and figuring out where trees need to be removed.

WSJ: Paul Mathews of Ecosign, Scouting the World for Killer Ski Slopes | Creating

It hasn't been given a name yet so lets reference it as "The Big Graph" where all lines intersect at 2020.

CNN: Just Imagine - Living Space: Your views