Както всяка програма, така и ACAD има собствена система за съхранение на информацията с която работи. B ACAD има доста стройна организация на данните. Най-основно информацията е разделена на няколко секции: HEADER, CLASES, TABLES, BLOCKS, ENTITIES и др.
В HEADER е записана основната информация за даден чертеж (файл) - версията на ACAD, с която е чертан чертежа, текущи стойности на голяма част от системните променливи и т.н.
В TABLES са дадени описания на обекти, като слоеве, типове линии, изгледи, текстови стилове и др.
В BLOKS са описанията на дефинираните блокове.
В ENTITIES са описанията на включените в чертежа чертожни елементи (примитиви).
Всички тези описания имат определен начин на организация. Те се задават така:
(ключ стойност)
за различните типове обекти има таблици със ключовете и възможните стойности или кодировка.
Eто описанието на една дименсия

((-1 . <Entity name: 4006ee30>) (0 . "DIMENSION") (5 . "6E") (102 . "{ACAD_XDICTIONARY") (360 . <Entity name: 4006eea0>) (102 . "}") (102 . "{ACAD_REACTORS") (330 . <Entity name: 4006eef0>) (102 . "}") (330 . <Entity name: 4006ecf8>) (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "0") (100 . "AcDbDimension") (2 . "*D1") (10 434.413 134.551 0.0) (11 349.763 270.322 0.0) (12 0.0 0.0 0.0) (70 . 33) (1 . "") (71 . 5) (72 . 1) (41 . 1.0) (42 . 319.969) (52 . 0.0) (53 . 0.0) (54 . 0.0) (51 . 0.0) (210 0.0 0.0 1.0) (3 . "ISO-25") (100 . "AcDbAlignedDimension") (13 239.654 389.756 0.0) (14 412.462 120.465 0.0) (15 0.0 0.0 0.0) (16 0.0 0.0 0.0) (40 . 0.0) (50 . 0.0))


10 - Definition point (in WCS)
11 - Middle point of dimension text (in OCS)
70 - Dimension type.
Values 0-6 are integer values that represent the dimension type. Values 32, 64, and 128 are bit values, which are added to the integer values (value 32 is always set in R13 and later releases).
0 = Rotated, horizontal, or vertical; 1 = Aligned;
2 = Angular; 3 = Diameter; 4 = Radius;
5 = Angular 3 point; 6 = Ordinate;
32 = Indicates that the block reference (group code 2) is referenced by this dimension only.
64 = Ordinate type. This is a bit value (bit 7) used only with integer value 6. If set, ordinate is X-type; if not set, ordinate is Y-type.
128 = This is a bit value (bit 8) added to the other group 70 values if the dimension text has been positioned at a user-defined location rather than at the default location

71 Attachment point:
1 = Top left; 2 = Top center; 3 = Top right;
4 = Middle left; 5 = Middle center; 6 = Middle right;
7 = Bottom left; 8 = Bottom center; 9 = Bottom right
72 Dimension text line spacing style (optional):
1 (or missing) = At least (taller characters will override)
2 = Exact (taller characters will not override)

41 Dimension text line spacing factor (optional):
Percentage of default (3-on-5) line spacing to be applied. Valid values range from 0.25 to 4.00

42 Actual measurement (optional; read-only value)
1 Dimension text explicitly entered by the user. Optional; default is the measurement. If null or "<>", the dimension measurement is drawn as the text, if " " (one blank space), the text is suppressed. Anything else is drawn as the text
53 The optional group code 53 is the rotation angle of the dimension text away from its default orientation (the direction of the dimension line) (optional)
51 All dimension types have an optional 51 group code, which indicates the horizontal direction for the dimension entity. The dimension entity determines the orientation of dimension text and lines for horizontal, vertical, and rotated linear dimensions.
This group value is the negative of the angle between the OCS X axis and the UCS X axis. It is always in the XY plane of the OCS

210 Extrusion direction (optional; default = 0, 0, 1)

3 Dimension style name

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