Callback flow version behavior

Summary:

When invoking an integration with the SOAP adapter utilizing a callback, how does the flow version actually work?

Content (required):

We have integrations that use the SOAP adapter to invoke another integration. It provides a callback operation. The callback attributes include "flow identifier" and "flow version". Are there any additional details about how "flow version" actually works at runtime?

We initially believed this flow version number must exactly match the version of the active callback flow, but one team member claims to have observed it succeeding when there is only one version of the callback integration flow that is of a different number.