While working on the classification of normal sequences, we discovered the following counter-example to [1, Theorem 4.2]. The base sequences S(k)∈BS(14,13), (k=1,2) given (in encoded form) by S(1)=0618616;1613441,S(2)=0618616;1613442
are both in the canonical form in spite of being equivalent. Indeed we have S(2)=σ2θS(1).

The error in the proof occurs in the last two sentences of the fourth paragraph on page 19. Namely, the claim that h2∈〈θ〉 is not valid. To correct this error, we just need to replace the condition (x) in Definition 3.1 with the stronger condition

if n is odd and qi≠2 for all i≤m, then qm+1≠2.

The last two sentences of the above-mentioned paragraph should be replaced by the following ones.

“Since h2 fixes the central columns 0 and 3, we may assume that qm+1(1), qm+1(2)∈{1,2}. If Q⊆{1,3,4,5,6,8}, then (x)^{'} implies that qm+1(1)=qm+1(2)=1. Otherwise 2∈Q and so h2 must fix the quad 2. Consequently, h2=1 or h2=θ and so qm+1(2)=h2(qm+1(1))=qm+1(1).”

After this correction, only S(1) has the canonical form. The program that we used to enumerate the equivalence classes did not suffer from the same error and our tables in the paper do not require any corrections. We have verified that all representatives listed in our tables (and the ones not included in the paper) are in the canonical form even when using the new definition. For example, note that only S(1), but not S(2), is listed in Table 7 (see item no. 332).

We point out three misprints: on the third line of the definition of (T4) on page 14, switch “even” and “odd”; on the fifth line of page 16, insert “switching A and B and” between “After” and “applying”; on the eighth line of page 16, switch the numbers 2 and 7.

ÐokovićD. Ž.Classification of base sequences BS(n+1,n)