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When setting out an equation, it is common to have a block of text that details the notation used, assumptions made and conditions under which the equation is valid.

For example, Newton's Law of Gravitation needs some qualifiers if you want to use it to tell you the force on an object due to another's gravity:

F = (G M m) / d 2


  • F = attractive force
  • G = gravitational constant
  • M, m = mass of two objects
  • d = separation of the objects' centres of mass

This only applies when the objects are not subject to relativistic effects and we assume no other forces act on the objects.

The word I'm looking for describes the text from "where:" to "objects". I had considered rubric, which means more "special instructions", but I don't believe this applies to descriptive, rather than instructional, text.

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It seems like a "key" or what we, in my high school geometry class called "givens." – Dan Feb 15 '13 at 16:07
@Dan I'd consider key (or legend) to apply to the first part, rather than the caveat in the last sentence. Givens certainly applies to all of it, though, as all of it is assumptions that are "given" when we apply the formula. – Jon Hanna Feb 15 '13 at 16:31
@JonHanna, legend rang true for me from your comment – Kristina Lopez Feb 15 '13 at 16:46
@KristinaLopez but again, a legend is an explanatory list, so I'd be inclined to to take it as not including the note on it being restricted to classical physics and ignoring relativistic effects. – Jon Hanna Feb 15 '13 at 16:48
Thanks for the comments! I think givens is probably the best suggestion so far, as both key and legend imply a list of one-to-one mappings, probably in a separate box or area to the main text. Might I ask what caused this question to be downvoted, so that I could improve in future? – Inductiveload Feb 15 '13 at 18:43
up vote 2 down vote accepted

Rubric has several meanings, and one of them is indeed an explanatory note or comment - separate to the sense of special instructions, that you mention.

Gloss likewise has several meanings, and one of them is an explanatory note. It's more often used when the gloss was provided by an editor or compiler rather than the original author, but not necessarily so.

(Originally rubric meant writing in red ink, or later other colours, as a form of emphasis or decoration; the variety of quite contradictory senses come from different figurative reference to that former custom).

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