Linearity is a restriction on CFTGs that requires the number of occurrences of every variable in the right-hand side of a rule be no more than 1, and nondeletion requires all variables in the left-hand side of a rule occur at least once in the right-hand side.
linear, nondeleting, monadic CFTGs are those with nonterminals of rank 0 and 1 only and with exactly one occurrence of a variable in every right-hand side of a rule for a nonterminal of rank 1.