2. Click the Line button in the drawing toolbar to draw an elevation symbol, just like a horizontal sign.

3. After drawing the elevation symbol, select "Drawing" in the menu bar.

4. Find the "Block" and click the "Define Attribute" command.

5. The system opens the "Attribute Definition" dialog box to set the attribute, where the mode is "Verification", the insertion point is the midpoint of the horizontal line of the roughness symbol, and then confirm, thus completing the elevation line of the landscape building.