Is this simply an illustration meant as a point-of-reference or does it imply the existence of a possible mach 6 aircraft designed for a similar role to the sr-71? Why include it at all? The document is dated 1980.
Found in SOC's scans of sr-71 derivative mission plan documents in the following thread.
http://www.secretprojects.co.uk/forum/index.php/topic,355.0.html