The Instruction operation "add" can be used to sum numerical inputs. Multiple inputs will all be added together.
The example below shows how a number of inputs will be arithmetically summed:
<instruction operation="add">
<input value="2" />
<input value="3" />
<input value="4" />
</instruction>
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The example below sums two inputs, but in this case the input values come from two stores ("three"=3 and "four"=4), so we have a store with the value of "three" (remember we could call the store anything else), which holds the number "3". The same applies to the value "four".
<instruction operation="add">
<input space="store" value="three" />
<input space="store" value="four" />
</instruction>
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