28.4.2 Assigning a value to a list-variable item
To specify the value of an item in a list, use an assignment that includes the index position of the item in brackets (see §28.3.2 Assigning values to macro variables):
<$$listname[index] = somevalue>
How the value is assigned depends on whether you include or omit a default value:
If you provide a value for list item 0 (zero), that value is used for any item in the list for which you have not specified another value. For example, suppose you specify:
Then if you use <$$mylist[15]>, without ever having assigned a value to the 15th item in the list, that value becomes “Error!”.
If you do not provide a value for <$$mylist[0]>, and you use <$$mylist[15]>, the value of <$$mylist[15]> is 0 (zero).
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