Continuity Angle Continuity Angle is the maximum angle the system will allow between the two normals while considering the two normals to be similar. A smaller value results in higher quality continuity, but more data. Ideally, for two surfaces to be G1 continuous at a point, the normal vectors would be co-linear. In reality, the system tries to minimize the angle between the vectors, since they will rarely be exactly co-linear at all points along the boundary. A smaller value results in higher quality continuity, but more data.
Curves Controls the distance curve on surface endpoints can be apart while defining a trim region.
If this gap is allowed to become too large, incorrect trim operations may result. If this value is too small, the trim operation may fail, since the curves on surface often do not define an exactly closed region. This value determines the distance within which polyset vertices must be in order to be merged. See Polygon Edit Vertex Merge for more information. We recommend NOT using this toggle unless you have a good reason for doing so and fully understand the implications.