Looking at some of the sample sw-description files in the documentation, there is always a version tag in the main top level software entity:
software =
{
version = "0.1.0";
target-1 = {
images: (
What is the purpose of this tag? Does swupdate read it at all? Looking through the documentation, the only reference to *software* versions is where you can specify version numbers for specific images and ask swupdate to only update them if their version number is different than that found in /etc/sw-versions. But that doesn't seem to apply to this top level version tag.