Related smells: Incomplete Tasks
Similarly to Chant that covers up imperfect fragments with comments in natural language, there could be pieces missing entirely from the grammar and replaced with comments. If the comments admit clearly what is missing, use searchable tags like “TODO” or “FIXME” and are intended to use as a backlog, the current practice is to refer to them as “self-admitted technical debt” [ICSME-2014-PotdarS].