§15.9. Multiple notations

Going back to our weight example:

A weight is a kind of value. 10kg specifies a weight.

The notation here is a single word, even if it contains digits as well as letters - "10kg". But it doesn't have to be one word. These would have worked, too:

10kg net specifies a weight.
10 kg specifies a weight.

In fact, we are allowed to have all three at once, as alternatives:

A weight is a kind of value. 10kg specifies a weight. 10kg net specifies a weight. 10 kg specifies a weight.

If we often have to deal with large weights, it becomes a little cumbersome to keep on writing something like "80000kg". An engineer would write "80 tonnes" for this. Similarly, we wouldn't like road maps to use light years, or speed limit signs to use furlongs per fortnight. So it's sometimes useful to provide a spread of different notations, at different scale factors, for the same kind of value. Here's one way of setting up the tonne, that is, the metric ton:

1 tonne specifies a weight scaled up by 1000.

This really is an alternative way to write the same thing: for instance, Inform will allow "25kg plus 3 tonne", the result being "3.025 tonne".

That's all very well, but a value like "3 tonne" reads a little oddly, even if it's correct in theory. Outside of scientific journals with old-school copy editing, most people would write "3 tonnes", not "3 tonne". Here's a better try:

1 tonne (singular) specifies a weight scaled up by 1000.
2 tonnes (plural) specifies a weight scaled up by 1000.

Now Inform will not only recognise both forms, but also use the right one when printing back.

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