1 Activate Your Free Trial!  Yawl. Yawl, two-masted sailboat, usually rigged with one or more jibsails, a mainsail, and a mizzen. In common with the ketch, the forward (main) mast is higher than the mizzenmast, but the mizzenmast of a yawl is placed astern of the rudder post, while that of the ketch is closer amidships.
System design is documented in the System Design Document (SDD). It describes design goals set by the project, subsystem decomposition (with UML class diagrams), hardware/software mapping (with UML deployment diagrams), data management, access control, control flow mechanisms, and boundary conditions.
In this phase the design team, testers and customers are plays a major role. Also it should have projects standards, the functional design documents and the database design document also. LLD -- Low Level Design (LLD) is like detailing the HLD. It defines the actual logic for each and every component of the system.