There is no official definition of what a "minor change" is. My working definition is "anything that my fellow contributors would agree is minor".

And the operative question is "Would they want to see this on Recent Changes (with 'hide minor changes' in effect?"

I mark these as minor: * Nearly all my grammar and spelling fixes * Copy-edits that DO NOT CHANGE the meaning

I usually don't mark these as minor: * Copy-edits that subtly correct a nuance of POV * Re-writes and re-phrasing which PROBABLY DON'T CHANGE the meaning, but which some other user might think is a sly attempt to inject my own POV (in a controversial article).

Ed Poor, aka Uncle Ed