<p>
    A token is a dependency.  It is something that a job must 'possess'
    before it can run, if that job needs that token.  You can create
    different types of tokens, giving each type a common name.  You can
    also specify how many instances of tokens of each type are to exist.
    For example, if the configuration file contained the following lines:
  </p>

  <div class="code"><pre><code>
   +-------------------------------------------------------
01 | ...   
02 | &lt;token T&gt;
03 |   number = 1
04 | &lt;/token&gt;
05 | &lt;token U&gt;
06 |   number = 2
07 | &lt;/token&gt;
08 | ...
   +-------------------------------------------------------
</code></pre></div>

  <p>
    ...it means that there are two types of tokens: 'T' and 'U'.  There is
    only one instance of token type 'T', and two of type 'U'.
  </p>
  <p>
    Given the above configuration, if your Family file looked as follows:
  </p>

  <div class="code"><pre><code>
   +-------------------------------------------------------
01 |start => '00:00', tz => 'GMT', days => 'Mon,Wed,Fri'
02 |
03 | J1( token => 'T')  J2 ( token => 'T' ) J3()
04 |
05 |-------------------------------------------------------
06 |
07 | J6(token => 'U') J5(token => 'U') J4(token => 'U')
08 | J8(token => 'T,U')
09 | 
   +-------------------------------------------------------
</code></pre></div>

  <p>
    ...then that means that job J1 and J2 both need a token of type 'T' to
    run.  But, there's only one instance of token T, so J1 and J2 cannot
    both run at the same time (even though they would, if they didn't rely
    on tokens).  The system will sort jobs alphabetically by name and
    choose the first in the list.  In other words, in this case, J1 will
    run first and J2 will only run after J1 completes (if no other job has
    taken the token first).  To be more accurate, J1 and J3 will run
    simultaneously, since J3 does not need any tokens.
  </p>
  <p>
    To be even more accurate, J1, J3, J4 and J5 will run simultaneously.
    This is because J4, J5 and J6 all rely on token U, but there are only
    2 instances of token U.  Even though J6 appears on the line before J5
    and J4, the system will choose J4 and J5 first, because they appear
    first in alphabetical order, and J6 will run after one of the other
    two have completed.
  </p>
  <p>
    Because the system always chooses the job with the smallest name
    (alphabetically), it is possible to experience 'resource starvation' -
    where a job with a 'larger' name could never get an opportunity to
    run, because there are too many other jobs with smaller names that get
    to run first by virtue of their names.  Future versions of TaskForest
    will implement heuristics to prevent resource starvations.
  </p>
  <p>
    Note that J8 relies on two tokens: T and U.  It will only run when it
    can acquire one of both tokens.  If it can acquire one, but not the
    other, it will release the first and try to acquire both at a later
    time.
  </p>
  <p>
    Finally, tokens can also be used to control the load on the machine on
    which taskforest is running.  If you've got several independent jobs
    that don't depend on each other, but which use a fair amount of
    resources, you can have all the jobs use the same token.  Then you can
    tweak the maximum number of instances of that token to a value that
    maximizes the number of simultaneous jobs without putting too much
    strain on the server.
  </p>