Editing Civil 3D 2019 (section)

== Interoperability ==

=== Opening an Autodesk Civil 3D 2019 Drawing in a Prior Version of AutoCAD Civil 3D ===

* Drawings saved in Autodesk Civil 3D 2019 can be opened in AutoCAD Civil 3D 2018. '''Note:''' Fixed vertical curves created with the Fixed Vertical Curve (Parabolic, High/Low Point, Parameter, Length) and Fixed Vertical Curve (Circular, High/Low Point, Parameter, Length) commands are not backward compatible with AutoCAD Civil 3D 2018. See the Profiles section below for more information.
* To open an Autodesk Civil 3D 2019 drawing and view the Autodesk Civil 3D objects in a version of the software prior to AutoCAD Civil 3D 2018, set the PROXYGRAPHICS system variable value to 1 in Autodesk Civil 3D 2019 to save the graphics with the drawing and then use the Save As command to save the drawing to a prior drawing file format. When you open the drawing in a prior version of the software, the Autodesk Civil 3D objects will be displayed as proxy graphics.

=== Profiles ===
Opening an Civil 3D 2019 drawing in Civil 3D 2018

* Fixed vertical curves created with the Fixed Vertical Curve (Parabolic, High/Low Point, Parameter, Length) and Fixed Vertical Curve (Circular, High/Low Point, Parameter, Length) commands are not backward compatible with Civil 3D 2018.
** You can use the Convert Curves command to convert the fixed parabolic curves so they are compatible with Civil 3D 2018, but the fixed circular curves cannot be converted and will be missing when the drawing is opened in AutoCAD Civil 3D 2018.
** If you do not convert the parabolic curves, those curves will also be missing when the drawing is opened in AutoCAD Civil 3D 2018. '''Note:''' Fixed vertical curves created with the Fixed Vertical Curve (Parabolic, High/Low Point, Parameter, Length) command in Autodesk Civil 3D 2019.1 are automatically converted to use two points and a parameter as their constraint type if you open the drawing in AutoCAD Civil 3D 2018. For more information, see the section above.
** After the curves are converted, they cannot be converted back to their original constraint type.

For more information, see [https://help.autodesk.com/view/CIV3D/2019/ENU/?guid=GUID-48BB985A-D671-43E3-81E9-91ADB0FD1BA2 To Change the Constraint Type of Vertical Curves for Backward Compatibility].

=== Subassemblies ===
Cant validation in rail subassembly PKT files

A validation process occurs in the [[Subassembly Composer]] for Civil 3D 2019 to check whether the geometry in rail subassemblies that depends on items which have ApplyAOR specified will be updated correctly. Open previously-created rail subassembly PKT files that use cant in the Autodesk Subassembly Composer and update them if needed.

For more information, see [https://help.autodesk.com/view/CIV3D/2019/ENU/?guid=GUID-28316475-19EA-426E-98DD-D87F72A8F0DE About Cant Validation in the Subassembly Composer] and [https://help.autodesk.com/view/CIV3D/2019/ENU/?guid=GUID-4B38B545-C0D2-407C-9022-4AEB1C20774C About Defining Cant for a Subassembly].