/usr/share/freeradius/dictionary.slipstream is in freeradius-common 2.1.12+dfsg-1.2ubuntu8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | # -*- text -*-
##############################################################################
#
#	For Slipstream dialup accelerator servers
#	Created based on
# 	slipstream_sp_6.0_installation_and_configuration_guide.pdf
#
#	$Id$
#
##############################################################################
VENDOR		Slipstream			7000
BEGIN-VENDOR	Slipstream
ATTRIBUTE	Slipstream-Auth				1	string
END-VENDOR	Slipstream
 |