jmh : I've given up using pure numbers for dates - I use 12 April 2000, wherever possible these days......one day I'll turn up and my ticket will be wrong by months. Is there an international standard?

Don't know about a standard but my use of the 20 Jan 01 style goes back to 1965 ... the US Armed Forces
used that style to avoid confusion when dealing with its personnel's being deployed to various countries.
When I did civilian travels it just seemed to work better all around than the all numerical style and other variations in use around the globe.
Once you get used to it, it's easy.
wow