Last update Dec29/19W3C//Dtd html 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd"> Master Style Guide: Chapter 11

Chapter 11
Working with flowcharts

This chapter discusses the issues involved with flowcharts, including:

Creating flowcharts
Formatting flowcharts
Using flowcharts in technical documents

These are discussed in the following sections.

Creating flowcharts

Flowcharts should be used to illustrate one or more of the following:

Data flow diagrams--The flowchart describes how data flows from one logical processing unit to another. These diagrams represent, for example, how input is transformed to output. They do not show control information. Data should not loop back on itself.
Process flow diagrams--The flowchart describes how a process works, or how data is handled by a sequence of processes. These diagrams represent, for example, how the data moves through a particular system. They may show control information if necessary.
Structure charts--The flowchart describes how an organization or how programs are structured. These diagrams represent organization charts or the data flow through a computer program.

Flowcharts can be created in any graphics-capable tool, including publishing tools (such as Microsoft Word or FrameMaker) and graphics tools (such as Visio).

Formatting flowcharts

The formatting of flowcharts depends on whether they are part of a document or the entire document as well as the complexity of the flowchart.

Using symbols in flowcharts

The following general symbols are used in flowcharts:

Rounded rectangles--Transformation center, where an input is transformed into an output. There should be a mnemonic label that describes the transformation associated with this symbol.
Rectangles--Data stores, where data of some kind is described. There should be a mnemonic label that describes the data represented as stored by this symbol.
Circles--User interaction. The interaction can be either input from or output to the end user.
Arrows--Direction of the flow. There should be a mnemonic label that describes the data flowing across the path represented by arrows. Arrows should only point in one direction and never be bi-directional.

Additional symbols may be used to represent devices (such as CD-ROMs, disks, or tapes).

Defining styles for flowcharts

In general, the following style rules apply to flowcharts:

Use a 2-point pen for all rounded rectangles, rectangles, circles, and all other containers.
Every container should have a shadow beneath it. The shadow may be a consistent gray or be color-coded at the discretion of the author. The shadow should appear below and to the right of the container, offset about 6 to 12 pixels from the container.
Use a 1-point pen for arrows.
Arrowheads should be filled solid, using a solid triangle as the pointer. Arrowheads should never be hollow (using a hollow triangle as the pointer) or just lines (using two lines as the pointer).

If the flowchart is contained within a technical document:

The flowchart should be treated as a Figure.
The flowchart should have a caption (such as "Figure 123 Data flow").
The flowchart should follow the general rules for illustrations discussed in Chapter 12, "Working with illustrations."
The flowchart may be left-aligned with the text above and below it or may be centered within the figure.
The flowchart should fit in the same space as the body text. The left margin should be 1 inch greater than the right margin.

If the entire document is a flowchart:

The flowchart should not have a caption.
The flowchart should follow the general rules for illustrations discussed in Chapter 12, "Working with illustrations."
The flowchart may be left-aligned on the page or may be centered on the page at the discretion of the author.
The flowchart should fit in the same space as the body text. The left margin should be 1 inch greater than the right margin.

Using flowcharts in technical documents

Flowcharts should only be used in technical documents when:

The flowchart conveys data in a form that is easier to read than any other form, such as tables or plain text.
The process being described has multiple branches, decision trees, dependencies, or loops.

Flowcharts generally define a process flow with a specific start, a specific completion, and specific procedures from moving from one container to another, be it by user input or a decision tree or a case statement.

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