Which QSF file is used in Quartus ?

[Altera_Forum]

In Quartus, with Assignment Editor, I can manage the pin locations, and I see, with the date, that my file project.qsf in my project folder is updated. 

Despite this, during the compilation, I have a error relative to a pin location (G2) which I don't use, and is not present in assignment editor, and is not present in project.qsf. Question: Where does this constraint come from ? Which qsf files can be used by default by Quartus ? Which one is read ?  Thank you, Arnaud.

[Altera_Forum]

THe .qpf points to the .qsf(or multple .qsf files if doing revisions). Project -> Revisions lets you change the .qsf it points to or create a new one. It's also possible to have a .qsf source another one, but not used very often and not overly recommended(since the GUI doesn't know which one to write to), but it has some good use cases. 

Most designs only have one .qsf. Does yours have more? What's the error?  Try closing Quartus and deleting the /db and /incremental_db, then re-running

[Altera_Forum]

You should review the entry for the respective pin in the pinout file. If the pin is user assigned, it will be clearly marked. 

 In a simple project that doesn't utilize revisions, you shouldn't have more than one .qsf file. So the question which is used can be easily answered.

[Altera_Forum]

Thank you for your answers. 

You're right, the simple is case is when there's no revision. BUT I have a revision (B). So I have in my project folder two files project.qsf and project_b.qsf. I suppose, depending of the revision, only ONE file should be read, but I saw, that, in some case, the second qsf file is used, for the first revision. When is it possible ? To avoid any confusion, I'm trying to avoid revision, and to have separate projects. I won't use revision anymore. For the moment it works, thank you again. Arnaud.