The Instruction operation "substring" is a string processing operation that creates a substring from an initial input value. It needs two further inputs to work, the second input defines the position and the third the number of characters.
The example below returns "he", so this means that our substring starts at position "0", which is "h" and counts 2 characters.
<instruction operation="substring">
<input value="hello " />
<input value="0" />
<input value="2" />
</instruction>he
The example below returns "is a substring", so this means that our substring starts at position "5", which is "i" and counts 14 characters, including spaces.
<instruction operation="substring">
<input value="this is a substring operation" />
<input value="5" />
<input value="14" />
</instruction>is a substring