We are constantly developing Zenario; we do our best to fix any reported bugs, interface problems, and to add new features.
Our version number system looks like this: 1.2.3x where:
Whenever the major or minor version numbers increment, it reflects that new features are present in the later version.
Where only the bug fix letter increments, it reflects bug fixes only. We do not normally add new features to a release in which only "x" has changed.
For example, 6.0.3 has different features from 6.0.2. But a release called 6.0.3b will only have bug fixes compared with 6.0.3a.
You should find the upgrade process from any version of Zenario from version 5.1 onwards to be very easy, with best support in our 6.0 range.
We recommend that you apply bug fix changes, especially if the fix contains a security update.