While egg markings have been around for some time, I only recently realised that these markings were standardised by the EU. Eggs in Switzerland typically have two lines, the first with the standard EU markings, the second with some additional information. The format is the following.
X is the production type (0 = organic, 1 = free range, 2 = indoors, 3 = caged),
CC is the ISO 3166-1 alpha-2 country code, and
ZZ…ZZ is a variable length farm identifier. The second line contains the date the egg was laid:
DD is the day in the month,
MM is the month number [1-12] and
YY is the year number.