<%row_num%> - a counter for what row is being looped, starts at 1.
<%rownum%> - an alias for <%row_num%>
<%first%> - boolean value that is true if this is the first row, false otherwise.
<%last%> - boolean value that is true if this is the last row, false otherwise.
<%inner%> - boolean value that is true if this is not first and not last.
<%even%> - boolean value is true if row_num is even.
<%odd%> - boolean value is true if row_num is odd.

Inside a loop i can use this; with rownum i can do something like:

loop ...
if rownum eq 4
do something

How i can choose from the array directly without a loop?