This is an example of line used in schematics. It’s laying out the second floor for the Akron Art Museum in Akron, Ohio.

Source: http://archidose.blogspot.com/2008/08/building-diagrams.html

This is another example of line used in schematics. It’s the schematic plan for an A-12 plane.

Source: https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/a-12/a-12-schematic.html