[runlevel1]

It's a common feature, but not formally standardized.

ED 3 isn't actually in the [ECMA-048] spec.

It was an xterm feature introduced in June 1999. Several terminal developers later adopted the feature. In April 2011, a Red Hat developer submitted a patch to the Linux kernel, modifying its console driver to do the same thing.

So it's not a formal standard, but it's universal on Linux since 3.0 and many terminal emulators have adopted it.

This history is covered in [clear(1)] from the ncurses project.

[ECMA-48]: http://www.ecma-international.org/publications/files/ECMA-ST...

[clear(1)]: http://man7.org/linux/man-pages/man1/clear.1.html#HISTORY

EDIT: Fix wording and formatting.

[JdeBP]

... none of which contradicts the point that the protocol does know about scrollback. The aforementioned developer, Petr Písař, got the implementation wrong, note.

* https://unix.stackexchange.com/a/375784/5132

* http://jdebp.uk./Softwares/nosh/guide/commands/setterm.xml