This pattern has to be implemented with a combination of a concurrence-like expressions and two or more 'if' expressions.

A concurrence-like expression is a expression that, like concurrence, applies all its children conccurrently (the merge behaviour is different from one to the other though).

    <concurrence>
       <if>
          <equals field-value="__subject__" other-value="credit approval" />
          <participant ref="reviewer-a" />
       </if>
       <if>
          <equals field-value="category" other-value="new plant" />
          <participant ref="reviewer-b" />
          <participant ref="reviewer-c" />
       </if>
    </concurrence>

Note that in this example, the first 'if' expression has no else child, it is optional.