The EMB code.

During October 1978, the French government issued a law about packages (namely:  "Arrêté du 20 octobre 1978 relatif au contrôle de certains métrologique préemballages" ), which appears retrospectively to have great importance on dating perfumes.

Since 1978-1979, all "Made in France" perfumes sport the word "EMB" (followed by a five-digit code) on the box. This "EMB" code will remain at least until the barcode (1989-1999), and even beyond.
Why is EMB code so important? For two reasons: the first is that in many cases can solve - roughly - dating questions: as you can see in the photographs, the same perfumes, in different years, can sport the word EMB on the box: so, it can be date "before or after" 1978-1979. It is useful when the batch code is erased.
The second reason of its importance is that, along with the classic barcode, the EMB code is an effective way to date perfumes.
Briefly said:  if your French perfume is without EMB code, it's  before 1978-1979 ;
if it is sport the EMB code but without the barcode, it's from the Eighties;
and if you can see the barcode (with or without EMB), it's after 1989-1990.

(Warning: do not confuse the EMB code with the "REF" or "reference " word , always reported on the box; then, remember that the EMB code is only valid for "Made in France" products.)

Paco Rabanne pour Homme
upper box with EMB code (and batchcode 1159. year 1981)
lower box without EMB code nor batchcode (mid-Seventies) 

"Equipage" by Hermes 

Top box without batchcode nor EMB code (generally dated to the Seventies) 

the lower box with erased batchcode (it indicated the year 1982) but with EMB code clearly visible: in this case, if you do not know the batchcode, you can generally dated "1980s"