- mesh to linear. **Convert to bi-quadratic** option does the same as
- **Convert to quadratic** except for that TRIA7, QUAD9 and HEXA27
- elements are created instead of TRIA6, QUAD8, and HEXA20 elements
- respectively. Note that the choice is available only if the selected
- mesh (or sub-mesh) contains both quadratic and linear elements, else the
- direction of conversion is selected automatically.</li>
+ mesh to linear. **Convert to bi-quadratic** creates some types of quadratic
+ elements with additional central nodes: TRIA7, QUAD9 and HEXA27
+ elements instead of TRIA6, QUAD8, and HEXA20 elements
+ respectively.</li>