The annotations are part of the system of doing corrections in registers. All corrections of a minor nature occurring at the time of the entry have to be numbered, obviously to prevent someone coming along later and altering an entry. Therefore, in this case, the correction would have been made at the time it was entered and is the first such correction in the register. Just to clarify, corrections of errors discovered, at the time of entry, before completion of the certificate are just numbered and initialed in the margin.
For errors discovered within a month of the entry being made then the Registrar (in the case of a Register Office marriage) in the presence of the relevant parties, or in their absence in the presence of the Superintendent Registrar and two other credible witnesses, corrects the erroneous entry by entry in the margin, without making any alteration of the original entry, and sign the marginal entry, adding date when the correction was made. In the case of a church marriage then it is the minister in the presence of the relevant parties. The reason for the corrections is written in the margin of the certificate. They are not entered in a separate book.
Stan