DataString is a container for a Microsoft XML Schema dt:r8 string attribute type. Length is a scalar real number "x" combined with applicable units. Angle is a scalar real number "t" combined with applicable units. The DesignXML Point represents a 3D, right-handed Cartesian coordinate point, but permits the absence (an implied 0.0 value) of a Z coordinate to represent 2D points. The DesignXML Vector represents a 3D, right-handed Cartesian coordinate vector, but permits the absence (an implied 0.0 value) of a Z coordinate to represent 2D vectors. A DesignXML Normal is a vector used to define the orientation of a 2D plane in 3D space. A Normal vector represents the Z axis of planar geometry such as circles, arcs, and text strings. The DesignXML Matrix3x3 element represents 3D orientation and scale. Each coordinate name uses two letters (for example "xz"). The first letter represents an input vector coordinate, and the second letter represents an output vector coordinate. One can also represent a 2x2 matrix for 2D rotation transforms by omitting all attributes with a name containning "z" (the omitted attribute values default to 0.0). See LinearCoordinateTransform. See LinearCoordinateTransform. A LinearCoordinateTransform represents a 3D linear transform from a linear coordinate system to another coordinate system. The LinearCoordinateTransform is defined by its contained Orientation (Matrix3x3) and Translation (Vector) elements. A LinearCoordinateTransform can also represent a 3x2 matrix for 2D transforms by omitting "z" elements and attributes. In fact, all elements are optional, with an empty matrix corresponding to an identity matrix. Planar entities such as text strings have a non-identity coordinate system to reflect an orientation that is not in the XY plane of the host coordinate system. ViewHeight is the vertical view size in model units, defined by the contained Length element. For perspective views, the size applies to the view plane that intercepts the target point. AspectRatio is the ratio of the view width to the view height, defined by the contained Length element. ViewDirection is the point of view, defined by two angles relative to the X axis and XY plane of the WCS. The contained Vector element describes the ViewDirection. TargetPoint is the focal point of a 3D view. FrontClip represents the front clipping plane in a 3D view. The front clipping plane is a plane perpendicular to the line of sight; objects between the point of view and the front clipping plane are clipped from view. The contained Length element defines the location of the FrontClip plane as a distance from the target point. BackClip represents the back clipping plane in a 3D view. The back clipping plane is a plane perpendicular to the line of sight; objects behind the back clipping plane are clipped from view. The contained Length element defines the location of the BackClip plane as a distance from the target point. PerspectiveViewingAngle represents the visible field of view in a perspective projection. For example, a PerspectiveViewingAngle value of 0 approximates an orthographic (infinite distance) projection, a value of 180 approximates a fisheye view, and a value of 40-60 gives a noticeable perspective quality to the view. WorldZDisplayAngle is the angle (the twist) from vertical that the model's Z axis (or Y axis for 2D views) appears. An upside-down view is 180 degrees. Every View specification must have a height in model units and a model target point, which is centered in the view. After that, however, Boolean attributes indicate the need for the other contained elements. For example, the value of the isTwisted attribute determines whether a WorldZDisplayAngle element is needed. A RenderSpecification identifies a RenderMode (Plan, Wireframe, Hidden, FlatShade, Gouraud, FlatShadeWithWireframe, GouraudWithWireframe) and View. ColorPalette is the color lookup table definition. ColorIndex represents an index into a ColorPalette element. TrueColor is the 24-bit color plus 8-bits for the alpha channel with choice of color space. Color is either a color index, or a true color, but not both. The Link element is used to associate elements in the common DesignXML channels with other bodies of information, including elements in other common channels, elements in a model channel, or even records in an external database. The most obvious usage is to indicate which application model element a Geometry3D or Facetted3D element corresponds to. For example, a Link might associate a Facetted3D Line with its AcDbXML Entity handle. Any number of Link elements can exist in a DXML file, so each application should add a unique prefix to the link name in order to distinguish it from links created by other applications. Autodesk Developer Network members should use their registered developer symbols in the Link name. Interpretation of links is the responsibility of the applications implementing them. Line segments are the set of points that lie directly between the two specified endpoints. An infinite line in space as defined by a point and a direction vector. A half line bounded by a point and extending in the direction of the vector. Vertices are the (minimum of two) points defining Polyline, Mesh, FacettedShell, and Body. The Vertices element effectively declares Point twice, which is necessary so that an XDR validating parser can enforce a minimum of two vertices. A Polyline is composed of linear segments with shared endpoints. Raster images are specified in separate files or URIs. A DesignXML Mesh element serves as the geometric frame for a RasterImage. A flat raster image is most easily attached to a 2x2 unclosed mesh. Raster image X and Y pixels are uniformly scaled to the Mesh's U and V coordinates, respectively. MxN quad polygon face meshes are specified as a matrix of vertices, optional vertex normals, and face and edge properties. The implicit ordering is M groups of N vertices, so that there are M rows and N columns. The corresponding parametric dimensions are U and V, which both have ranges of 0.0 to 1.0. The U dimension is 0.0 at the first vertex in each row, and is 1.0 at either the N-1 vertex (if unclosed in the N direction) or the first vertex (if closed in the N direction). The same relationship applies to the V coordinate along the M rows of vertices. The number of Mesh Vertices must equal mSize * nSize. The rest of the contained Mesh elements are optional and independent from one another, but if present, must be present in the numbers indicated. Raster images are always applied to a mesh. The number of NormalVectors must equal (mSize * nSize). The number of EdgeProperties must equal (mSize - isClosedM + 1) * (nSize - isClosedN + 1) The number of FaceProperties must equal (mSize - isClosedM) * (nSize - isClosedN) A FacettedShell consists of arrays of face elements that are closed boundary paths specified as an array of indices into an array of shared vertex locations. Shared vertex normals can be optionally specified. Overriding edge element properties can also be specified. The same index refers to a vertex, and the edge that starts with the vertex. The final edge goes from the final vertex to vertex 0 (the first vertex). All specified faces are visible; holes exist where there are no faces. If this shell represents nonlinear geometry, MaximumDeviation specifies the maximum distance the shell geometry can displace from the actual geometry. If the shell represents linear geometry, 0.0 is a viable length value. The FacettedFace element contains a group of VertexIndex and ElementPropertyIndex elements that define a closed loop of linear edges, with optional overriding properties. Both VertexIndex and ElementPropertyIndex have valid ranges of 0 through (n-1) where n is the number of corresponding elements. The number of Vertices points must be at least ((the maximum VertexIndex used in any FacettedFace element) + 1). The remaining arrays NormalVectors and ElementProperties are optional and independent from one another, but if present, must have the same size as the Vertices element. The number of NormalVectors must equal the number of vertices. The number of ElementProperties must be at least ((the maximum ElementPropertyIndex used in any FacettedFace element) + 1). Text is strings with size, orientation and font information. The default coordinate system for text is defined by the following: start position (origin), oblique angle (italicized clockwise from orthogonal Y axis), height (Y Axis Scale factor), baseline direction (X Axis), and normal (Z Axis). The FacettedSubmodel is a building block used to apply transforms to other geometry. You use a FacettedSubmodel by referencing it via a FacettedSubmodelReference. A FacettedSubmodel transform can be applied to every Facetted3D channel object (not including FacettedSubmodel elements themselves), plus Color and Link. The name attribute is a unique id that will be referenced. The Color element specifies the default color for the geometry. FacettedSubmodelReference references a FacettedSubmodel via the submodel idref identifier. The quadraticCurveType attribute defines whether the arc represents the outer edge arc curve segment, the chord segment between the two arc endpoints, or a sector. The contained Circle element defines the Arc center and radius. The StartVector's initial point is the Circle's center point. The Arc startpoint is defined by the StartVector's intercept with the Circle. The SweepAngle defines the inclusive arc angle difference between the startpoint (and angle), and the endpoint (and angle). For example, a sweep angle of 90 degrees defines a quarter of a full circle. The Ellipse is 3D or 2D, depending on the value of the Normal element. The number of control points should equal (numberOfControlPointsU * numberOfControlPointsV). The number of Knot occurrences should equal (numberOfKnotsU * numberOfKnotsV). BRep topology is defined externally. The systemId attribute points to a file containing ACIS Brep data. A Submodel is a building block used to apply transforms to other geometry. You use a Submodel by referencing it via a SubmodelReference. A Submodel transform can be applied to every Geometry3D channel object (not including Submodel elements themselves), plus Color and Link. The name attribute is a unique id that can be referenced. The value of the Color element defines the default color for the geometry. SubmodelReference references a Submodel via the submodel idref identifier.