So, at the top of the form there is a place to select a project number and then see the details (company name, address, service, and start time) of that project. When the listbox selection is changed, nothing happens. The form has to be refreshed before the details will match the selected project number.
You could put the refresh button in the same form as the listbox, however if that is done everytime the button is hit a popup window will appear saying "the contents of the form have changed, do you want to save the changes before refreshing?" (or some language like that). If instead the refresh button is put on a subform, it will refresh both the subform and the parent form with no annoying popup windows, and this is what DACM has done.
In the top form still, it is possible to change the start date, start time, and service type of the project. If you changed the date or time and then closed the form, a popup box would appear saying "the content of the current form has been modified, do you want to save your changes?" If instead you press the 'save' button and then closed the form, you would avoid the popup box.
Also, when using the form, any date/time or service type changes are automatically saved when the record being viewed is changed (when the project number in the listbox is changed and then the refresh (->) button is pressed), however many people feel more confidence in their data being saved if they are able to push a button that says "save".
The company name and address are not editable in the top form. The bottom form is used for this purpose. When a company name is selected, no changes are made to the address listbox; the form has to be refreshed. After the refresh button is changed, the bottom listbox is populated with the addresses related to the selected company name. Again, the button is placed on the subform to prevent the annoying popup boxes. Actually, this button does the exact same thing as the other refresh button, but it is convenient to the user to have a button next to each listbox being interacted with.
The "display results" button is a refresh on the main form - after a different address is selected at the bottom, pressing this button shows the address at the top. I think the popup is avoided because the change was made in the subform and not in the mainform.
The save button in the bottom part of the form does the same thing as the save button in the top part of the form, again having one in both areas just for convenience for the user.
Does that help?