Selecting a file extension

[zachattack05]

I am adding a feature to my application that allows users to backup an entire SQL database, as well as include application settings with that backup file. My dilemma is choosing a good file extension to use.

The over-used .bkp type could cause conflicts in systems that have applications that already create a file with that extension.

I know that Microsoft recently started creating 4 character extension .docx etc... and was wondering what people thought about using extensions with 4 or more characters as well as just selecting file extensions in general.

[Momerath]

Use whatever makes you happy. Microsoft added the 'x' to things to indicate that they are now in XML format vs. their old formats. Use 'backup' if you want :)

[zachattack05]

I considered just using .databkp. I just want to make sure that the extension is:

1) easy to remember for a user
2) unique enough that conflicts with other programs are limited.

I'll have to think about this a bit more.