Root Sentence: A root S ("sentence") is an S that is not dominated by a node other than S.

Root Transformation: A transformation (or a transformational operation) that moves, copies, or inserts a node C into a position in which C is immediately dominated by a root S in derived structure is a "root transformation" (or a root transformational operation).

Structure-Preserving Transformation: A transformation (or a transformational operation) that introduces or substitutes a constituent C into a position in a phrase marker held by a node C is called "structure-preserving."

Local Transformation: A transformation (or a transformational operation) that affects only an input sequence of a single nonphrase node C and of one adjacent constituent C' that is specified without a variable, such that the operation is not subject to any condition exterior to C and C', is called a "local transformation" (or a local transformational operation).

Nonlocal transformational operations are called Major Transformational Operations.