Trees

Description: InFocus uses the concept of Trees throughout its design. Trees are hierarchies of related data. The two areas that make use of Trees are organizations and projects. An organization is typically depicted in a chart. Typical stations on the chart might be divisions, offices and departments. Projects, in turn, are subdivided into smaller segments, often referred to as phases and tasks. This link-type relationship is often analogized to a tree. Considering the following project tree.

(9801) - Empire State Building    ------- (10) Schematic Design       -----  (A) CAD Work

                                                                                               -----  (B) Research

                                               -------  (20) Design Development   ------ (A) Meetings

                                                                                               ------ (B) Modeling

                                               ------- (30) Contract Admin.          ------ (A) Meetings                    

                                                                                               ------ (B) Site Visits        

                                                                                               ------ (C) Rework          

In the above diagram we have a project linked to three phases, each of which are linked to two or more tasks. Each item on the tree is called a node. Therefore, Empire State Building, schematic design, and cad work are all nodes.

The numbers and letters in parenthesis are generically referred to as node codes. So 9801 (typically referred to as the project code) is a node code as is 10 for phase schematic design.

Since some nodes can have the same code (e.g., cad work and meetings) it is necessary to refer to nodes not only by their code, but also by what branch of the tree they live on. The way InFocus accomplishes this is to cite each code along the branch to the node in question. For purposes of clarity, a separating character (also know as a delimiter) is used between each node code. This notation is called a path. An example of a path would be 9801-10-A. In this example, the project is Empire State Building, the phase is Schematic Design, and the task is  CAD work. A hyphen is used as the delimiter.

The next terms to understand are parent-child relationships. Nodes can have parents and children. For instance, CAD Work has an immediate parent called Schematic Design but no children. Schematic design has an immediate parent called Empire State Building and two immediate children called Cad work and research. The use of the word immediate means adjacent to. In other words Empire State building is a non-immediate parent to CAD work since it is related to CAD work indirectly through Schematic Design.

The relative position of a node to the beginning of the tree is called the level. In the above example, 9801 is on level one, phases 10,20 and 30 are on level two. All other nodes are on level three. Levels can be labeled so we can refer to them in real world terms such as project, phase and task.

Another thing to note is the uniqueness of the node code. It must only be unique in respect to its immediate parent. Since level ones nodes have no parent they must be unique with respect to all other level one nodes in the system.

Two other terms used in this manual in regards to trees are top nodes and bottom nodes. Top nodes (also known as root nodes) are level one nodes (nodes with no parent). Bottom nodes (also known as terminal nodes) are nodes with no children.

Finally, a tree segment starting from a particular root node is called a breakdown structure.

In InFocus, we refer to a project structure as the work breakdown structure (WBS), and the organization as the organization breakdown structure (OBS).