Relevant to applications that use generation (typically translation applications). Value should be a list of three positive numbers [$\langle$Start$\rangle$, $\langle$Increment$\rangle$, $\langle$Max$\rangle$], such that both $\langle$Start$\rangle$ and $\langle$Increment$\rangle$ are less than or equal to $\langle$Max$\rangle$. Generation uses an iterative deepening algorithm, which initially sets a maximum derivation length of $\langle$Start$\rangle$, and increases it in increments of $\langle$Increment$\rangle$ until it exceeds $\langle$Max$\rangle$.

Default value is [5, 5, 50].