關于ASTM D1500的翻譯問題

附件A1當中有幾段關于比色計的要求，愣是沒看懂，了解的大佬麻煩給我這個菜鳥解答下~謝謝~~~~~
首先是第一段：A three-field instrument shall show three illuminated areas in the field of view. Two areas shall be filled with light transmitted by two different color standards, and these shall be disposed symmetrically about the third area which shall be filled with light transmitted by the sample. The rectangular dimensions of each of the three areas shall be the same, and the left- and right-hand corners of the full field of view shall be rounded with radius not exceeding half the vertical dimension. The illuminated areas shall be separated in a horizontal direction by vertical lines so that the closest portion of the sample area and any one of the color standards illuminated areas subtends the eye of the observer not less than 0.3° nor more than 0.6°.
問題：這里面提到的0.3°~0.6°的范圍，指的到底是使用者的眼睛到哪個位置的角度？是到視場的邊緣，還是視場的中心？
第二段：Each illuminated area in the two-field instrument shall cover a circle of diameter subtending at least 2.2° and may be enlarged to any size provided that no two illuminated points in the field of view are separated by a distance subtending more than 10°. In the case of the three-field direct
viewing instrument, the subtending angles become 2.6° and 6.4°, respectively.
問題：這一段是真的一頭霧水，第一句就怎么都想不通什么意思？
第三段：The angle subtended by a line of length d, in a plane perpendicular to the line of sight, and separated from the eye of the observer by a distance D, is given in degrees by 57.3 d/D. The angle subtended by the image of this line, seen by viewing it through an eyepiece of magnification M, is given in degrees by 57.3 Md/Di, where Di is the distance between the eye of the observer and the plane of the image.
問題：這一段里提到了57.3 d/D和57.3 Md/Di，既然附件A1是對D1500測量方法中使用的比色計作出了要求，那么這里我的理解是d/D的值應該等于57.3，同樣的，Md/Di也要等于57.3，不知道這么理解對不對？另外，對于這一段里提到的d/D/Di這三個參數(shù)，我也理解得不到位，望解答！
最后，向大佬低頭，有大佬出來給新手解答一下嗎？看在我出生到現(xiàn)在發(fā)的最長的一個帖子的面子上~~~最后，附上D1500-2007的文檔和找到的部分翻譯。