Pre-emption
RFC 794, “Pre-emption”, is an Informational document published in September 1981 by V.G. Cerf. The canonical text is published by the RFC Editor.
What “Informational” means
Published for the general information of the community. It does not define an IETF standard and carries no standards-track status.
The canonical text of RFC 794 is hosted at rfc-editor.org. Available in TXT,HTML.