Just stumbled upon Evernote Synchronization via EDAM while researching sync strategies. As part of the spec when there is a conflict while syncing entities, Evernote tries to perform "field-by-field" merge:
If the existing tag has the “dirty” flag, the user has created a tag in the service and in the client with the same name while offline. Perform a field-by-field merge or report the conflict for resolution
How does a field-by-field merge works? AFAIK, Evernote does not keep track of specific field updates, it just mark whole records with a "dirty" flag, what happens if there is an update from the server to one field while the client updated another one?
The Evernote service does not do a field-by-field merge. The document is just saying that as part of your own sync process, you could either do that or report the conflict to the user.