You can use construction geometry to help you draw and constrain a profile, but the construction geometry is not used to construct the surfaces for the feature. When the feature is created, the construction geometry is ignored. The Construction command is used to change a profile element or sketch element into a construction element.
Construction elements use the double-chain line style so you can distinguish them from other elements.
For example, you can use 45 degree construction lines to control the location of the tabs on the profile or sketch.
The construction lines make it easier to edit the location of the tabs, but the construction lines are not used to produce the solid model.