I'll post this as an answer because it can be thought of being closely related to known work on pairs, although I'm not sure really if it has been worked out before. I realized that Quine-Rosser pairs can be adapted to suite extending them to implement tuples of any ordinal length! The tuples I'll describe here would be what could be thought of as being the simplest genuine extension of the Quine-Rosser pairs. Statement: for any ordinal $\alpha$, there is a tuple of length $\alpha$, and there will be no limitation (unlike the tuple in the question) on which set can be a projection of it. Let $D$ be the set of all Ordinals. Define functions $F_i$ for $i \in D\setminus \{0\}$ as: $F_i(X)= [X \setminus D] \cup \{d+^+(i+^+1)| d \in D \cap X \} \cup \{i\} $ and were $``+^+"$ is "incremental ordinal addition", defined as: Define: $\alpha +^+ \gamma = max (\alpha+\gamma, \gamma + \alpha)$ Now the tuple $t^{\alpha}(S)$ whose projections are entries $s_i$ of the sequence $S$ from $\alpha \to V$ is defined as: $ t^{\alpha}(S) = \{F_i(x)| x \in s_i \in rng(S) \land i \in \alpha \}$ Now to retrieve back the $i^{th}$ projection from the pair, the smallest ordinal member of the elements of the pair would serve as the indicator of the projection, so take the set of all elements of the tuple having ordinal $i$ as the smallest ordinal in them, and taking the converse function $F^-1$ over those would yield the $i^{th}$ projection of the tuple. So simply: $i^{th} (p) = \{ x | F_i(x) \in p \}$ This tuple works in the most general manner that a tuple can work in NF\NFU, as well as in NBG, MK set theories. However, in ZF and its extensions, it is equivalent to the tuple mentioned in the question.