I believe YYYY-MM-DD is even less ambiguous than YYYY/MM/DD.

Correct. Slashes mean it's a yank date and going to be backwards. Dashes hint that it's going to be (close to) ISO standard.

_Algernon_ 6 days ago | parent | next [-]

And it doesn't use a path-separator character for the date.

tom_ 6 days ago | parent | prev [-]

Slashes are used for dd/mm/yyyy as well. Dashes are indeed better if you want a separator. or use the separator-free ISO 8601 syntax.

	▲	worik 4 days ago \| parent [-]
		I just use the number of peta-seconds since I was born....