  Recently, Cohen, Haeupler and Schulman gave an explicit construction of
binary tree codes over polylogarithmic-sized output alphabet based on
Pudl\'{a}k's construction of maximum-distance-separable (MDS) tree codes using
totally-non-singular triangular matrices. In this short note, we give a unified
and simpler presentation of Pudl\'{a}k and Cohen-Haeupler-Schulman's
constructions.
