Siara: Very strange! I have never saved to or imported a .MIF file
It's not customary to use MIF as the working file format for an active project, except perhaps in scenarios where authors are using mixed versions of FM. I've never seen it used in a .book, and suspect that there may be some downsides. It is commonly used for exporting a project for translation & such.
re: It doesn't sound like it will be an issue.
Project-wise, it won't be, unless it becomes one. On Save after modification, for example, does it cause a Save-As dialog to pop?
Anyway, there is a real issue here, which is that it appears that Adobe doesn't document these book menu icons. I wasn't able to find anything in either the FM7 print manual, or a later on-line. I've never paid much attention to them on account of this.
These icons are intended to make you more efficient. The icon design, text and current aspect convey a lot of information about the file type, whether generated or not, and perhaps other status. It's not terribly efficiency-promoting if the average author doesn't know what they are saying, and doesn't know where to find out. Perhaps one of the aftermarket authors could add a summary to their FM book.
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