"Regulatory Synonym" listings in Table 302.4 of 40 CFR 302.4

What determines whether a "Regulatory Synonym" is listed for a substance in Table 302.4 of 40 CFR 302.4?

In general, no entry is made in the "Regulatory Synonym" column of 40 CFR 302.4, Table 302.4 for a substance if only one chemical name is used to identify that substance under the environmental statutes and implementing regulations referred to in CERCLA section 101(14). If, however, a substance has more than one chemical name listed under these other statutes or regulations, then: (1) each chemical name will appear as a separate entry in Table 302.4 (as discussed above; and (2) each entry will include the other chemical name(s) (appearing as separate entries in Table 302.4) for that substance in the "Regulatory Synonym" column.