Bracket Erasure Convention

The Bracket Erasure Convention is a convention proposed in Kiparsky (1982) stating that internal brackets are erased at the end of a lexical level or stratum.

Comments
As a consequence of this convention words become phonologically inert at the end of each lexical level, i.e., they can no longer be affected by cyclic phonological rules. After bracket erasure, morphologically derived words are treated as though they were underived. In Kiparsky's view this inertness extends to morphological processes, and word formation rules therefore do not have access to the internal structure of words derived at an earlier level. Thus, Siegel's (1978) Adjacency Condition or Williams' (1981a) Atom Condition can be reduced to the Bracket Erasure Convention.

Link
Utrecht Lexicon of Linguistics