When it comes to incremental releases, ExtendSim 10 is upwardly compatible. For example, a model or block created in ExtendSim 10.0.8 can easily be read in by ExtendSim 10.0.9.

However, there could be application or block changes in newer releases that would impact file readability in older incremental releases. For example, if you save a model in ExtendSim 10.0.9, you may not be able to successfully open it in ExtendSim 10.0.8 (and definitely not in ExtendSim 9 or earlier).