The parameter passed there is part of the Open args, which is a string variable that can be passed TO the form as it opens.
For instance, I might have a form Projects, in which I have a button to Create New Task, which opens up a seperate form (Instead of using a subform) and I want to let that form know that the new task's master object is the project, so I pass the project ID in the openArgs.
Then in my form's Load event I do:
- Me.tb_ProjectID.DefaultValue=Me.OpenArgs
Now as for vbModal, it really by itself means nothing when passed as part of the openargs, unless you specifically add code in the form using the OpenArgs (As example above)
When something is MODAL it means that it is a popup that catches the focus, I.e. you cannot click on any other access forms, until you have closed the form. Usefull for instance if you don't want your code to proceed until "something" has happened in the popup and user has closed the form. A standard msgbox for instance is modal.
Edit:
So try checking the form being opened, and do a search in its code for OpenArgs.