An attribute held against each line string which governs whether the line string is to be used in model formation and contouring. For example, a change of grade line such as a top of bank would usually be flagged as contourable (i.e. as a breakline), where as an overhead power line would be flagged as not contourable (i.e. not a breakline).
A breakline may be either hard or soft.
- A hard breakline represents a sharp edge, such as a top of kerb
- A soft breakline represents a more rounded edge, such as a river edge.