An erratum (plural: errata) is a correction of a published text. The term originated in the pre-digital age, and signified a mistake, by either the author or the printer, that was identified in the time between printing and distribution. If the mistake was significant enough that it could not be deferred to a later printing, yet not so significant that it required a complete revision, then an additional page for errata would be printed and tipped into each book before it left the printing house.
See also: Erratum on Wikipedia.
For CDISC standards, an erratum is a correction to a mistake made in a published standard, that which was identified after it was published on the CDISC website, and which would have been corrected in the current version had it been identified prior to publication. Updates, revisions, substantive¹ corrections, and other changes of enough significance to require a cycle through the standards development process are not errata, and thus are not included on the pages below.