Open a model. Copy / Paste Special *MASTER into a 3D
Shape (Representation2) using the CATIA_SPEC option.
Update the 3D Shape.

Double-click Sketch.1 in the specification tree. After
the conversion, tangency is maintained because there is an evaluation
of the Sketch before.

Constraints can be applied when:
- there is a line-circle or circle-line sequence
- and the angle in-between has a vivicity tolerance from 0.5 to 2.5 degrees
Therefore, there is an evaluation of the deformations made upon the Sketch
according to the V4 vivicity tolerance (2.5) and the V6 vivicity tolerance
(0.5). An edge (already smooth for CATIA V6) will not be taken into account.
For instance:
- if the first V4 angle <=2.5 and the resulting V6 angle is >0.5,
therefore vivicity is changed: it was smooth becomes sharp.
- or if the first angle >=2.5 and the next angle is <0.5, therefore
vivicity is changed: it was sharp becomes smooth. This process is called
"variation" and it is not recommended to apply constraints because there
are too many movements.
When there is no constraint to be applied, there is no evaluation
of the sketch.