"Feature Percolation Conventions" [Lieber, R., 1980, ‘On the Organization of the Lexicon’, MIT, Cambridge] a. Convention I: All features of a stem morpheme, including category features, percolate to the first nonbranching node dominating that morpheme. b. Convention II: All features of an affix morpheme, including category features, percolate to the first branching node dominating that morpheme. [...] c. Convention III: If a branching node fails to obtain features by Convention II, features from the next lowest labeled node automatically percolate up to the unlabeled branching node. [...] d. Convention IV: If two stems are sisters (i.e. they form a compound, features from the right-hand stem percolate up to the branching node dominating the stems. [...] The conventions have the net effect of labeling the highest branching node in a word tree with the category and features of the outermost affix if the tree contain affixes, and with the category and features of the right-hand stem if the tree contains only stems.
- Lieber (2004), Pag. 210-211