Candela frequency and that has a radiant intensity in that direction of watt per steradian. The definition describes how to produce a light source that (by definition) emits one candela, but does not specify the luminosity function for weighting radiation at other frequencies. Such a source could then be used to calibrate instruments designed to measure luminous intensity with reference to a specified luminosity function. An appendix to the SI Brochure makes it clear that the luminosity function is not uniquely specified, but must be selected to fully define the candela. The candela is sometimes still called by the old name
Does exactly what it says on the tin Does exactly what it says on the tin "It does exactly what it says on the tin" was originally an advertising slogan in the United Kingdom, which then became a common idiomatic phrase. It colloquially means that the name of something is an accurate description of its qualities. It is akin to the previously existing phrases "by name and by nature" and "it lives up to its name". It originated in a series of television advertisements by the woodstain and wood-dye manufacturer Ronseal, initiated in 1994 and still being broadcast . The slogan was created by Liz Whiston and Dave