Variables
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A variable is a symbol that begins with a left angle-bracket (i.e., <), ends
with a right angle-bracket (i.e., >), and contains at least one alphanumeric
symbol in between.  For a production to be satisfied, all occurrences of the
same variable must match the same symbol or number.  In the previous example,
<p> must match the same value in the first and second conditions.  Two
different variables can match the same symbol unless there is an explicit
test that they are not equal (using <>).  In the example, <p> and <s> could
match the same symbol, although it is unlikely.  Below are example legal and
illegal variables in Soar.

Legal variables    Illegal variables 
{<p>}    {<>} 
{<1>}   {<1} 
{<variable1>}   {variable>} 
{<abc1>}   {<a b>}