GNU/Linux Desktop Survival Guide
by Graham Williams
SADT stands for Structured Analysis and Design Technique which is a trademarked and copyrighted by Softech Inc. A SADT model is a collection of diagrams organised in a tree structure. Each SADT
diagram is composed of Boxes (representing activities) connected by Flows (arrows) representing flows of materials, data or information.
The SADT sheet provides the three basic components required for drawing SADT diagrams: Activity/Data Flow, Activity/Data box, and Flow Annotation. The activity/data flow can be one of several styles, including Normal, Import Resource, Imply Resource, Dotted Arrow, or with Disabled Arrows. The default is Normal but can be changed in the Object Defaults window (double click the Activity/Data Flow button).
Flows have different roles in relation to the activities. The middle mouse button (or control right click on Windows) is used to add or remove segments.
The default flow is Vertical-Horizontal-Vertical. It is sometimes useful to do a bit of middle mouse button clicking to build a Horizontal-Vertical-Horizontal variant which can then serve for copy-and-paste in your diagram. A non Vertical-Horizontal-Vertical flow will be shown in black instead of the default grey. While this is not in the original SADT specification it is often handy to untangle a heavily loaded sheet (with more than 4 or 5 functions—though these sheets should be avoided).
Connections points can be added to or removed from the sides of an SADT box by clicking the middle mouse button. Function identifier (A0, A1, etc.) can be changed by opening the box properties. The associated function (the contents of the box) is changed by simply selecting the box and typing any text.