Once the new messages are in, the instances of use of the old messages will need to be fixed. For instance, page sizes listed by Special:ListFiles are not in kilo/mega/giga/etc. bytes, they are in kibi/mebi/gibi/etc. bytes. Users would appreciate having a preference switch in their user settings that allows them to see file sizes using either set of prefixes.

@Nikerabbit "Translators are free to use correct units, and the base is explained in the message documentation." Not always. https://translatewiki.net/wiki/Intuition:X%27stools-memory/qqq is a good example. It is highly doubtful that this message's parameter is actual megabytes—because it deals with memory. I raised the question in 2017 and the non-answer was that "This message is a part of old Xtools tool, please contribute translations of new Xtools [instead] via Special:Translate/xtools". If the message is that old, why is still in the frigging database?

@Aklapper Changing the task (232095) name to "Message should use binary prefix symbols (SI units)" is misleading because binary prefixes are not SI. They are IEC.

May be related to http://phabricator.wikimedia.org/T88088 ?

May be related to http://phabricator.wikimedia.org/T111199 ?