However, there's no governing authority on file extensions, so, it really could be almost anything. The extension 'ins' MAY be a clue (it's possible that this is an index file of some sort...)
can you open it with notepad? if so, does there appear to be a structure to the file contents? I've imported quite a few non-documented data files into various databases, but, it's almost always a lot of detective work to uncover any hidden structure to the data.
"Lisa, in this house, we obey the laws of thermodynamics!" - Homer Simpson
"I have my standards. They may be low, but I have them!" - Bette Middler
"It's a book about a Spanish guy named Manual. You should read it." - Dilbert
I've opened the file with an hexadecimal editor, but it hasn't any string and has a very strange size: 799 bytes. It's a file of a group of files and I almost discovered the relations between the others, but this doesn't seem relacted with others (I tried to found some numbers equal but with no results).