Sometimes a standard may need a technical or editorial correction to be made. IEEE accommodates these needs using a Corrigenda or an Errata Sheet.
Corrigenda corrects a technical error, as well as a semantic error. Since they are correcting technical errors, Corrigenda do need a PAR and go through a consensus ballot.
Errata sheets are separate pages issued after an IEEE standard has been approved and published. They correct typographical or editorial errors that have been found in that particular IEEE standard. An Errata sheet does not require a PAR and a consensus ballot.