The International System of Units usually only permits the use of a capital letter when a unit is named after a person. It is often difficult to distinguish between the character "l" and the digit "1" in certain fonts or handwriting, and therefore both the lower-case (l) and the upper-case (L) are allowed as the first letter in litre. 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.
Woolner perpetrated the April Fools' Day hoax in the April 1978 issue of "CHEM 13 News", a newsletter concerned with chemistry for school teachers. According to the hoax, Claude Litre was born on 12 February 1716, the son of a manufacturer of wine bottles. During Litre's extremely distinguished fictional scientific career, he purportedly proposed a unit of volume measurement that was incorporated into the International System of Units after his death in 1778.