http://www.rfc-editor.org/rfc/rfc1797.txt
RFC 1797: Class A Subnet Experiment, 1995-04-01T23:00:00-00:00There appears to be some interest in experimenting with subnetting the class A addresses. It is suggested that conducting an experiment now to identify and fix any software that does not properly handle subnetted class A addresses would be useful and important. This document defines an Experimental Protocol for the Internet community. This does not specify an Internet standard of any kind.