Most software continues to be developed after the first version comes out.
So if you have purchased a later version of the software you can expect to be able to read files created from earlier versions. This is 'backward compatible'
Quite often the later version of the software will offer to convert the older file into its newer format. Once you do take up the offer, you will no longer be able to read the file using the original version.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Backward Compatible