One ISO standard that does not appear to be supported by Thunderbird is a non breaking space, this is formed in Word (for example) by CTRL+Shift+Space. This allows a large number to have a non breaking space, eg 1 000 000, as in my number one million to the left has non breaking spaces created in Word. If this number is at the end of a line it will keep the number together. This ISO recommended way of writing large numbers both positive and negative is used in many countries including France, South Africa and Australia. It is also recommended by NIST in the USA. When I do CTRL+Shift+Space in Thunderbird nothing happens. In Wikipedia they use "   " to achieve the same thing. http://en.wikipedia.org/wiki/Non-breaking_space