Dictionary of Computer and Internet Terms: railroad diagram
railroad diagram
a diagram illustrating the syntax of a programming language or document definition. Railroad-like switches are used to indicate possible locations of different elements. Figure 215 shows an example illustrating the syntax of an address label. First name, last name, and City-State-Zip Code are required elements, so all possible routes include those elements. Either Mr. or Ms. is required, so there are two possible tracks there. A middle name is optional, so one track bypasses that element. There may be more than one address line, so there is a return loop track providing for multiple passes through that element.
