Addendum to progress notes IP, OP, Office etc

I am looking for a citation I recall reading a while back.
It said addendums may be added to progress notes at any time as long as the record is not under scrutiny of an audit. The citation mentioned that addendums show be done in as timely a manner as possible, however, if an error/omission is picked up on internal audit, the record can be amended.
I know that I saved a copy for future reference, but I cannot put my finger on it.
Does anyone recall seeing something like this from an official source?

addendums

https://www.noridianmedicare.com/provider/updates/docs/doc_Guides_amend_records_reprint.pdf;

http://www.avera.org/pdf/avera/MedicareGuidelinesAmendedRecordsJune09.pdf;

http://www.ahima.org/infocenter/guidelines/ltcs/5.1.asp