freebeer
You are seeing two differently-aged 256-pixel-squared tiles, where at the left, Po starts to be displayed westbound, but then le-Line eastbound takes over.
If I were to attempt to give the actual dates of the two tiles, I would probably lose this comment so painfully typed in.
Which probably is not a bad result, come to think of it.
In some weeks, the labels will match and this comment, like the electrons it wasted, will have hundreds if not thousands of mappers stymied until the end of time trying to decipher your meaning.