# Lines and faces: superpositions and intersections

## Intersections and superpositions

The bordering property of the geometry building module entails the interdiction of the intersections of lines, of faces and of lines with faces.

The superpositions of line/face type, i.e. lines belonging to a face, or face/face type, i.e. faces belonging to a face, are authorized.

These different cases are presented below.

## Intersections, superpositions of lines

The intersections and partial or total superpositions of the lines presented in the figure below are not authorized and in this case the construction of faces is not possible.

## Lines belonging to faces

The lines belonging to faces are authorized. An example is presented in the next figure.

Lines L5 and L6 are internal lines of face F1.## Intersections of line/face type

The intersections of line/face type are not authorized, but they do not block the construction of faces and volumes.

## Faces belonging to faces

Faces belonging to faces are authorized. An example is presented in the figure below.

## Intersections of faces

The intersections of faces are not authorized and thus the construction of volumes is blocked. An example is presented in the figure below.

The faces of the parallelepiped intersect the circular face of the inner cylinder of the torus.

Thus, the faces and the volumes cannot be built.

## Intersections of faces: to avoid problems

To avoid the previous problem, it is possible to ignore some faces in the moment of volumes building.

This method is presented in § Nature of points, lines and faces.

## Available corrections

Flux owns tools to correct the intersections and superposed entities in automatic or manual manner, presented in section Geometry importation (IGES, STEP, DXF, STL, FBD, INTER formats).