gml:ArcString 

An ArcString is a curve segment that uses three-point circular arc interpolation ("circularArc3Points"). The number of arcs in the arc string may be explicitly stated in the attribute numArc. The number of control points in the arc string shall be 2 * numArc + 1.
The content model follows the general pattern for the encoding of curve segments.

Element Information

Model

(gml:pos | gml:pointProperty | gml:pointRep | gml:posList | gml:coordinates)
Children: gml:coordinates, gml:pointProperty, gml:pointRep, gml:pos, gml:posList

Attributes

QName Type Fixed Default Use Inheritable Annotation
interpolation gml:CurveInterpolationType circularArc3Points optional
numArc integer optional
numDerivativeInterior integer 0 optional
numDerivativesAtEnd integer 0 optional
numDerivativesAtStart integer 0 optional

Source 

<element name="ArcString" type="gml:ArcStringType" substitutionGroup="gml:AbstractCurveSegment">
  <annotation>
    <documentation>An ArcString is a curve segment that uses three-point circular arc interpolation ("circularArc3Points"). The number of arcs in the arc string may be explicitly stated in the attribute numArc. The number of control points in the arc string shall be 2 * numArc + 1. The content model follows the general pattern for the encoding of curve segments.</documentation>
  </annotation>
</element>

Sample