I believe the rules merely say that failing to fulfil a fixture constitutes "Misconduct"
Which constitutes a *very* broad church indeed. Possible actions arising from that are in Section 92. Which basically say anything or nothing can be done
84 The League’s Disciplinary Powers
84.1 The League has the power to bring disciplinary proceedings for misconduct against any Club, Official, Player and/or any other individual subject to these Regulations by:
84.1.1 imposing a fixed penalty in accordance with the provisions of Regulation 87;
84.1.2 referring the matter to a Disciplinary Commission appointed under Regulation 89; or
84.1.3 referring the matter to the Football Association in accordance with Regulation 88.
84.2 The same facts or matters may constitute a breach of more than one Article, Regulation, order, requirement, direction or instruction referred to above. The League may bring a charge or such charges as it sees fit.