# PreserveIsoCurveMethod enum

Namespace: [Rhino.Geometry](https://developer.rhino3d.com/api/rhinocommon/namespace/rhino.geometry.md) · Assembly: [RhinoCommon](https://developer.rhino3d.com/api/rhinocommon/assembly/rhinocommon.md) · Since v8.21

```cs
public enum PreserveIsoCurveMethod
```

The way the surface iso-lines align with the target

## Values

| Name | Value | Description |
| --- | --- | --- |
| Automatic | 0 | If the trim is on an iso direction use [PreserveIsoCurveMethod.MatchTarget](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.preserveisocurvemethod.md), else use [PreserveIsoCurveMethod.Perpendicular](https://developer.rhino3d.com/api/rhinocommon/type/rhino.geometry.preserveisocurvemethod.md) |
| MatchTarget | 1 | The surface tangent will be parallel to the surface derivative in U- or V-direction |
| Perpendicular | 2 | The surface tangent will be perpendicular to the target edge |
| Preserve | 3 | The surface tangent will not change |