The documentation for 8.3+ simplified declare expressions speaks of "atomic" targets at the bottom of the section. Atomic calls to mind indivisibility in computer science contexts, reserved for a handful of situations such as transactions, "atomic use cases", etc. What is the implication here?

The documentation's example target appears to be a scalar property in an embedded page. Is non-atomic supposed to mean "a property on an embedded page"? If so, what's the difference between that and needing to specify the page context, handled in the section above?

Or am I reading it wrong and the intent is to contrast scalar with vector?

As a secondary question, we became accustomed to dire performance problem warnings for the declare expression "whenever used" setting. Does the introduction of "simplified" declare expressions imply this issue has been eliminated?