The database (actual filemaker file) is by default set to YourDatabaseName.usr (usr can be set to any 3 or 4 letter extension)
OR multiple databases if your solution is not one database.
If you copy or remove the YourDatabaseName.usr and rename to YourDatabaseName.FP7 it will open in Filemaker 7 thru 11.
In Filemaker OPEN Dialog you can select "All Files" and it will open the .usr file.
If you create WIN and Mac runtimes with the same name, extension, and bind key, you can move the DATABASE file from one FOLDER WIN / Mac to the other.
"In the runtime building process, FileMaker does not alter your original solution files during this process. What it does is create copies of your solution files that are bound to a limited FileMaker engine. A runtime solution will only work with the files that are bound to it. So if your solution have four FileMaker files, they will work great together with they are bound together.
The linking between the runtime engine and the FileMaker files is accomplished via a bind key. This “under the hood” attachment allows your runtime solution to interact with a multiple file FileMaker solution. This binding process can work for existing runtime solutions.
You can bind new files to a solution as long as you keep the bind key consistent. So it is possible to add a new file to a customers runtime solution as long as the bind key is consistent. This is commonly used for additional user interfaces that use a common centralized data file."
VERY GOOD READ
Using FileMaker 12 Runtime files with FileMaker Go 12
Thanks for the information.
From a practical standpoint, What does this 'look like'? From reading the forums it seems like I would FIRST create a Windows runtime and copy the binding key. THEN, I would transfer the 80mb Win runtime folder to my Mac. Then I would create a Mac runtime, using the copied Win Folder as the 'target' but would USE THE COPIED BINDING KEY from the windows RT creation. Is this right?