# 11.11.2 Coordinate Lines

Topic Version | 1 | Published | 09/11/2015 | |

For Standard | RESQML v2.0.1 |

RESQML provides support for parametric points and parametric lines. If the node points are defined parametrically, then each pillar must have a parametric line defined. The parametric point construction uses the mapping from coordinate line index to parametric line index, which is identical to the mapping from coordinate line to pillar.

- For an unfaulted grid, the count and indexing of coordinate lines is identical to that of the pillars.
- For an IJK grid, there are four pillars per column of the model.
- For an unstructured column-layer grid, there is an arbitrary number of pillars per column, which are specified explicitly as part of the grid description.

- For a faulted grid, the count of coordinate lines is increased by the number of split coordinate lines. The indexing of the coordinate line is defined by the “columns per split coordinate line” jagged array construction. The pillar index for each split coordinate line is also specified. With these two pieces of information, the topology and geometry of the faulted grid cells can be inferred from the specification of the unfaulted grid description.
- In order to have a well-defined index for the cell faces in the case of a faulted grid, a column edge index must be defined first. This is part of the faulted column-layer grid construction.