LandXML & Civil 3D tips, clarifications and important matters to remind me while programming

LandXML angular direction :
Unit is always Decimal Degrees
Positive values only, counter clockwise, zero to East

LandXML horizontal alignment elements :
Are set in CoordGeom
Common to Civil 3D are Line, Curve and Spiral (others are Irregular line and Feature ?)

LandXML horizontal alignment element Spiral :
Civil 3D supports only Spiral.SPItype=Clothoid

LandXML horizontal alignment element Curve (Civil 3D Arc) :
Civil 3D supports only crvType=arc

Civil 3D api can be viewed only using Chrome. IE does not show side window elements !?
http://docs.autodesk.com/CIV3D/2018/ENU/API_Reference_Guide/

Civil 3D alignment simple type entities are subentities of more complex ones like SCCS etc.

LandXML theta angle :
is Pi-SpiralIncludedAngle in degrees and is always positive and less than Pi.
Spiral Included Angle is the angle between Short and Long tangents and is always positive and less than Pi.