Hello John. Regarding whether it should be annotated or not, it depends.
If the base is put in a .BASE file, people are going to run extmerge (3-way tool), in that case it mustn't be annotated, to not confuse the tool as you say.
If the base is put directly in the file (like --show-base currently puts a BASE region in the file, between <<<TREE and >>>MERGE-SOURCE), then people are going to edit the file with their editor, then the annotation doesn't hurt (they'll delete those BASE lines anyway), I don't know if it would help.
By the way, thank you very much for looking into this!
Hello John. Regarding whether it should be annotated or not, it depends.
If the base is put in a .BASE file, people are going to run extmerge (3-way tool), in that case it mustn't be annotated, to not confuse the tool as you say.
If the base is put directly in the file (like --show-base currently puts a BASE region in the file, between <<<TREE and >>>MERGE-SOURCE), then people are going to edit the file with their editor, then the annotation doesn't hurt (they'll delete those BASE lines anyway), I don't know if it would help.
By the way, thank you very much for looking into this!