Use the placement controls on the contextual tab to control the elevation of split lines when shape editing elements.
After the datum is selected, set the elevation or offset value to establish the position of the split line.
For more information, see Split an Element for Shape Editing.
This feature was suggested by customers on the Ideas forum and is described on the product road map.
Use Tab Select to select a chain of split lines. Once selected, adjust the elevation of the entire chain of lines with the controls on the ribbon. Use this selection and editing method to adjust contour lines of toposolid elements.