Former series 1947-1975. Diplomatic plates were of heavily embossed thick metal, with CD and a serial above the year and below ESPAÑA (or vice versa).
Former series 1977-1999. Embassy number 27 = USA
Current series CC = Consular Corps (15 = Korean Republic)
Consular Corps (04 = Algeria)
OI = International Organization (31 = Gabon)
TA = Administrative and technical personnel