You can export your company to a text file, so that you can easily share it with other people or store it for your own use on a computer that does not have M.Ind on it.
You cannot import the text file back into M.Ind. If you want to keep the company you made so you can change it later, you should save it as well as exporting it.
If you want to share the text file with people using Microsoft Windows, you should select the box Create Windows-compatible files in the Preferences. If you do not, Windows users will likely see the whole exported text file as one long line instead of with each unit appearing on a line of its own. Selecting this option is not necessary when you want to share the text files with other Mac users, or with people using a Linux PC.