The status of modeling reverse combustion along coal fissures is reviewed in some depth. There is evidence that such propagation is highly sensitive to irregularities in the structural state of the coal. Under some circumstances radiative heat transfer can control the process. Exploited region development is classified into processes at non-permeative and permeative fire faces. At permeative fire faces forward combustion along fissures can enhance burnout and rubbelization. The paper is directed mainly at shrinking coals but problems with swelling coals are briefly discussed.