The first form in WIMOVAC displays a list of the available model dialogs. By selecting one of these the user is able to launch the requested model component and interact with the model via simple inputs. In WIMOVAC model dialogs consist of a number of standard Windows elements (figure 3). A menu line which provides access to the graphing and printing facilities (figure 3i), the model parameters database (figure 3ii), and the hyper-help system(figure 3iii). Other components of a dialog include multiple choice selectors (figure 3ix), formatted input boxes (figure 3iv), context sensitive labelling and action buttons (figure 3v,vi,viii). In keeping with the Windows environment it is possible to use the mouse to select model dialog controls or to use the tab key to move from control to control on the form and the space bar to toggle between values. Numerical entries from the user are range and type checked for validity before acceptance for a model run.

A WIMOVAC model module can be run with the default settings by simply clicking the start button on the appropriate dialog (figure 3vi) or properties of a model may be explored by varying parameters. This is done in WIMOVAC by editing either input values, multiple choice selectors or the action buttons on the model dialog form itself (figure 3), or by modifying the model parameter database (figure 4). Because WIMOVAC includes over 100 potential input parameters, it is most practical to have two levels of entry. The most commonly modified parameters and initial conditions for a sub-model are accessible on the model dialog form itself. These and all other parameters can also be accessed by entering the model parameter database. Changes made on the form are only active for the current model run, permanent changes must be made in the model parameter database, using the File-exit and save changes option, on completion (figure 4). In situations where a parameter occurs in both the model database and on a model dialog form the value outlined on the form takes precedence when the model is run.

Traditionally model parameter files have been manipulated as complex ASCII files and required a separate ASCII file text editor. There are a number of problems with this approach however. These include difficulties with starting a separate text editor program within the modelling environment, and the discontinuity of user interface that this represents, and the complex formatting and abbreviations generally used in such files. To avoid these problems and to meet the specifications on ease of use, WIMOVAC, employs a parameter database editor in a spreadsheet format which is consistent with the format and user interface of the rest of WIMOVAC. This spreadsheet like mode of operation will be familiar to anyone who has used a modern spreadsheet package such as Lotus 123 for Windows or Microsoft Excel. The WIMOVAC parameter database editor is called in a seamless fashion from the model dialog menu and appears as an integral part of the modelling environment itself. The parameter database editor has facilities to cut, copy and paste information from other applications using the Windows clipboard and to search for text entries and values within the parameter database. It is also possible to printout either selected areas or the whole of the database to any printer supported by Windows. A typical search of the database entries takes less than a second on a 25MHz 80386 machine.

Currently the parameter database input form consists of a dialog with four columns. The first column contains a plain English description of the parameter, units of the parameter, and where applicable the range of acceptable values (figure 4vii). The second column contains the parameter value (figure 4vi) and the third the literature citation from which the parameter was obtained (figure 4v). The fourth column contains a textual reference to the parameter which is used by WIMOVAC to search for the parameter within the database (figure 4iv). The user may modify any of these settings and include their own notes and experimental findings.

WIMOVAC saves any changes made to the parameter database to two separate disk files. The first of these is a plain ASCII, tab delimited, file for use with applications outside of WIMOVAC. The second file is a specialised ASCII file compatible with the string handling facilities built into Windows and is the file used by WIMOVAC model dialogs. The Windows string handling functions are highly optimised and make it possible to search for hundreds of model parameters within the database in just a few seconds. The WIMOVAC parameter sheet also allows copies of the parameter database to be saved to disk under any MS-DOS compatible file name and this makes it possible to set up multiple test scenarios using different parameter datasets and to permanently store these on disk. Saving all the model parameters needed to perform a model run to a single file, in this manner, makes it easier for a researcher to send all the information needed to duplicate a piece of work to other workers for validation and discussion.

When the start button on the model dialog is pressed WIMOVAC executes the program code that contains a symbolic representation of the model system under investigation. If the model code requires more than a few seconds in order to finish a progress bar is shown. Upon completion of a simulation run WIMOVAC loads the graphing module and transfers over the results of the simulation to the graph. The graphing module is central to results handling in WIMOVAC and provides an automatically formatted graph, with labelling and scaling performed from information gathered automatically from the model dialog options selected by the user. The graphing module defaults to a simple line graph of the results but using the appearance-gallery menu option on the graph form a number of graph types can be selected (figure 5iii). These include 2D and 3D pie, line and area charts in addition to gantt, log, scatter, polar, bubble and tape charts. The graphing module offers a number of curve fitting functions as standard including 1-9^th order polynomial fitting, logarithmic, power, exponential and inverse curve fits.

The graphing module offers only limited scope to modify the font selection and sizes used to label output graphs and so is not intended to provide a replacement for packages designed to produce publication quality graphs, but rather to provide an easily interpreted visual representation of the simulation results. In order to facilitate communication between the graphing module and other packages WIMOVAC has a menu option which allows a copy of the simulation results to be passed to other applications via the Windows clipboard (figure 5iii). The results may be passed in either a columnar, tab delimited format suitable for use within a spreadsheet or as a graphical image. WIMOVAC supports both standard and device independent bitmaps and offers the option to use the scaleable Windows metafile format.

The graphing module is also able to create an ASCII data file of simulation results. WIMOVAC produces a columnar ASCII file that can be conveniently read by both MS-DOS and Windows based spreadsheet or graphics programs. The information in each column is determined by user selection of options on the module dialog form. The columns are separated by a tab character which is compatible with most DOS and Windows based programs. Titles are introduced to the top of the file to indicate the nature of the data in the file and to each individual column to indicate the columns contents. In addition to this WIMOVAC is able to save a graphical image of the graph to disk in either bitmap or metafile image.

The graphing module is capable of printing in either landscape or portrait mode in either monochrome, dithered colour, or full colour to any Windows supported printer. A Windows common printer dialog procedure built into WIMOVAC makes it possible to select printer and output characteristics prior to printing.