Who knew!

Perhaps you should go on to say it's hexadecimal RGB shorthand and that when concatenated it should be interpreted as the long hand which gives rgb(00h,0Fh,FFh) which is blue with a little green.

Shorthand hex notation is commonly used in HTML styles, eg p { color:#000; } gives paragraphs black text.

Alas, my first thought was 0x0fff, or 4095, even though I use 3-digit color codes quite a bit in HTML and CSS.

oh!