Page "Litre" Paragraph 4

In many English-speaking countries, the most common shape of a handwritten Arabic digit 1 is just a vertical stroke ; that is, it lacks the upstroke added in many other cultures.

Therefore, the digit ' 1 ' may easily be confused with the letter ' l '.

Further, on some typewriters, particularly older ones, the unshifted L key had to be used to type the numeral 1.

Even in some computer typefaces, the two characters are barely distinguishable.

This caused some concern, especially in the medical community.

As a result, L ( uppercase letter L ) was adopted as an alternative symbol for litre in 1979.

The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L, a practice that is also widely followed in Canada and Australia.

In these countries, the symbol L is also used with prefixes, as in mL and µL, instead of the traditional ml and µl used in Europe.

In the UK and Ireland as well as the rest of Europe, lowercase l is used with prefixes, though whole litres are often written in full ( so, " 750 ml " on a wine bottle, but often " 1 litre " on a juice carton ).