论述了地图符号的说明注记和数字注记的集合及属性，并分别给出了这两种注记的识别方法。
Sets and properties of explanation and numeral notes of map symbols are discussed. The recognition methods of two notes are given too.
本注记用一种几何解释说明了在处理狭缝和窄带问题时运用细线近似的合理性。
A geometric explanation is presented to explain the reasonableness of applying thin wire approximation to narrow slots and strips.
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