The E seems legitimate, cp. with E in legend. Pierson makes no interpretation. Perhaps Extremadura (Salamanca) after the union
of the crowns. Pierson has good photos of this and other mint marks.
Rights
CopyrightHolder: American Numismatic Society
License: Public Domain Mark (images)
Rights: No Copyright - United States
1969.222.1259http://numismatics.org/collection/1969.222.1259mb_physical,osm,imperiumobjecthttp://numismatics.org/search/id/https://numismatics.org/themes/mantisdisplaypk.eyJ1IjoiYmhpaWJuZXIiLCJhIjoiY2xlZWZqZmJjMGdheDNwcW1qaHM2MWZ4cSJ9.oR2ZyKdE7BYKzQkjiotNSghttp://numismatics.org/search/manifest/1969.222.1259American Numismatic Society