About Undefined Nodes
“Undefined Nodes” are grid and solid model nodes that have been removed by a filtering process such as polygon clipping, distance filtering, surface filtering, etc.
Grid nodes with an Undefined Z-value of Null (-1.0e27) and Solid nodes with an Undefined Z-value of - Null (-1.0e27) will be ignored/skipped by all RockWorks programs thereby rendering them invisible within maps and diagrams and not included within any computations (e.g. grid/grid math, solid/solid math, volumetrics, etc.).
Grid nodes with an Undefined Z-Value of anything other than Null (-1.0e27) will not be ignored by RockWorks programs. The purpose of allowing for non-Null Undefined Nodes is to provide a means to specify;