A value expression is a mathematical equation that returns a numeric (real or integer) result. The expression consists of a set of operators, functions and keywords. Value expressions are typically used in a network plot to proportionately size a network element based on the expression result.
A value expression may also be a multi-value expression. This is one where more than one value result is calculated, and is used to display and compare multiple values for a node or link. The expressions of a multi-value expressions are separated by a semi-colon ";".
Some example value expressions are as follows:
Centroids and Nodes
[node user data 1] ui1
[Initial boardings and final alightings] inboa;fiali
[Link length] sqrt(sqr(xj-xi)+sqr(yj-yi))
[Auto Volume (in hundreds)] round(volau/100)