External Element Reference Allison Barnard FeeneyThomas Thurman February 26, 2013 # revision history jan 21, 2013 status: technically complete for review, editorially incomplete jan 23, 2013 included Peter Denno comments jan 28 more formatting Feb 5 Allison comments Feb 25 Abstract updated Introduction updated Feb 26 Reorganized doc, updated architectural description section to merge per new contents sketch Feb 28 added tables for EXPRESS, Mar 8 replaced bracket figure, added legends to other figures, removed material from backup, minor cleanup April 19 incorporated comments from Allison, added figure and caption data. created zip file including external figures. left figures in document for reviewers. February 24, 2017 initiated experiment on Authorea using text insert.