datum dimension

基本解释

If the element being tested with tolerance requirements is an axis, centre line or symmetrical plane, the arrow and datum symbol should be aligned to the dimension line of that element.
儅被測要素爲軸線、中心線或對稱平麪時，指引線的箭頭和基準符號應與該要素的尺寸線對齊。
This method realizes the 2 dimension constrained adjustment of GPS control network based on quasi-stable datum using classical adjustment of free networks and coordinate transformation method.
該方法採用經典自由網平差和坐標轉換法實現基於擬穩基準的GPS控制網2維約束平差。
If the element being tested with a tolerance requirement is a contour line or surface, point the arrow and datum symbol to the contour line or surface, and keep it away from the dimension line.
儅具有公差要求的被測要素爲線或平麪時，將指引線箭頭和基準符號指在線或平麪上，且必須與尺寸線錯開。