40 CFR §97.181

1. (a)Except as otherwise provided in §§ 97.101 through 97.104, §§ 97.106 through 97.108, and subparts BB and CC and subparts FF through HH of this part, a CAIR NOX opt-in unit shall be treated as a CAIR NOX unit for purposes of applying such sections and subparts of this part.
2. (b)Solely for purposes of applying, as provided in this subpart, the requirements of subpart HH of this part to a unit for which a CAIR opt-in permit application is submitted and not withdrawn and a CAIR opt-in permit is not yet issued or denied under this subpart, such unit shall be treated as a CAIR NOX unit before issuance of a CAIR opt-in permit for such unit.