ETA = Edited to add (not "estimated time of arrival", the more common usage)
I sometimes use ETC, edited to correct, but that hasn't caught on.
ETA: And here's the LessWrong acronym list -- we need to link it from the front page.
Where I live, ETC stands for Electronic Toll Collection and is posted at the entry ramp of toll-roads equipped appropriately.
What's wrong with just using "Edit: additional note goes here"
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