### 2.3.1. Defined Constants

The following are defined in the header file cfxImport.h, which should be included in the import program.

#### 2.3.1.1. Element Types

There are currently 4 types of elements, which are identified by the number of nodes: Tetrahedrons (4 nodes), pyramids (5 nodes), wedges or prisms (6 nodes), and hexahedrons (8 nodes). The element types may be identified by the defined constants:

    #define cfxELEM_TET  4
    #define cfxELEM_PYR  5
    #define cfxELEM_WDG  6
    #define cfxELEM_HEX  8

The element node ordering and local face numbering follow Patran Neutral file conventions for element descriptions.

#### 2.3.1.2. Region Types

Regions may be defined in terms of nodes, faces or elements, based on the type argument to the `cfxImportBegReg` or `cfxImportRegion` routines. The three types are defined by the defined constants:

    #define cfxImpREG_NODES  1
    #define cfxImpREG_FACES  2
    #define cfxImpREG_ELEMS  3

Node and Face regions define 2D regions of the imported mesh. Element regions define 3D regions of the imported mesh.

It is best to use face regions to define 2D regions of the mesh and element regions to define 3D regions of the mesh.

Node regions will be automatically transformed into a face region by the import process. This transformation requires the node IDs specified to define vertices of valid element faces. If no element faces can be constructed from the defined node region the node region will be deleted.

Note: Due to the limited topological information recoverable from a set of nodes it is not advisable to define 2D regions internal to a 3D region using nodes. In this case it is advisable to use Face regions.

Node regions are specified by a list of node IDs.

Face regions are defined by a list of face IDs. These face IDs are a combination of an element ID and a local face number in the element.

Release 18.2 - © ANSYS, Inc. All rights reserved.