" xxx"? That's the same in ASCII and UTF-8.

OP is asking what are the line-drawing characters encoded as e.g: "┌" and "┐".

Since the charset returned by the app is UTF-8, these will be interpreted and encoded as UTF-8 and not whatever "ASCII - Extended" means.

that would be completely correct... sorry. the export options now read "ASCII Basic" and "ASCII Extended", and "Basic" generates plus signs for corners, as of now. I feel like the behavior might have changed. Extended option seem to use 0xE294xx range for lines.

1: https://gist.github.com/numpad0/7880ad1e3ed32b91d1ccf9c3374f...