A short mathematical note by Ralph Griswold on collation (interleaving) of t-sequences, the integer sequences he used to design weaving patterns. It explains stacked collation, where the second sequence is offset by the bound of the first so their terms occupy disjoint t-sets, and flat collation, where terms are interleaved without offset. It gives an example collating a binding sequence with a constant sequence, shown as grid figures, and ends with a summary of the notation S ~i T, S ~ T and S ~0 T.