Wireframe line properties can be assigned on three different pages in the Properties window depending on the effect you are trying to achieve.
The highest precedence is applied to line properties assigned on the Color Zones page. When the Apply zones to lines of constant check boxes on the Color Zones page are enabled, those properties take precedence over any other assigned line properties.
Line properties assigned in the Plot Lines of Constant section on the General page have the same precedence as the line properties assigned on the Z Levels page. If the options on the Color Zones page are not used, the next highest precedence are selections on the General page or Z Levels page, whichever is changed last. The Z Levels page colors are only used on Z lines.
Line properties for wireframes are controlled from the wireframe properties in the Properties window. The X and Y line properties specified in the Plot Lines of Constant section on the General page are applied over the entire surface without regard to the relative level of the surface.
To assign X and Y line properties so that they change over the vertical range of the surface, set the line properties on the Color Zones page. Color zone line properties vary based on Z values in the grid file.
Use the Line Properties in the Plot Lines of Constant section on the General page to apply the same line properties to all lines of constant Z without regard to level. To apply Z line properties that vary according to elevation, use the options in the Z Levels or Color Zones pages.