The user is given continual guidance and assistance during data entry. For parameters that are difficult to estimate the user may be advised of literature to aid in selecting a value, or an explanation of a parameter and some proposed values may be shown on the screen. If there are other ways to pick the value, typically if the parameter is a function of other variables, the equation is shown to the user.
The user interface is intelligent and offers expert system capabilities based on the knowledge of the software developers and experienced users. For example, as various graphical elements are connected to form a network, XP filters the user’s actions so that a network that is beyond the scope of the model is not created. The general philosophy is to trap any data problems at the highest possible level - at the point the data is created by the users.
In addition to the well-known and accepted benefits of input and output graphics, the xp environment provides the user with expert data checking facilities. The following sections outline the checks used by XPSWMM and XPStorm.
Knowledge based data filtering prevents the creation of an illegal network or modifications that would result in an illegal network. The network is checked to meet the following constraints:
Data entered via text items is checked against the data type expected for that item. If a number is expected then the text string entered is interpreted to see it follows the rules for numerical strings. For example, if an integer (whole number) is expected, then invalid characters such as non-digits, decimal points etc, are trapped and the data is not accepted.
Pure text strings or comments are accepted as entered.
The syntax for numerical strings follows the usual rules. Larger-magnitude numbers can be entered via exponential notation.
xp indicates floating-point numerical items by adding a decimal point if this hasn't already been done.
As data is entered it is filtered on two levels:
After all the data has been entered and the user attempts to solve the networks the inter-relationship of all data is checked for consistency, again at two levels: