Mediterranean Gull

Green ring with white 4 alpha-numeric code.

* for France starting “country-letter” is 'R' and then three letters or numbers, but always at least one number.
* for Belgium starting “country-number” '3' and then letter-letter-number. Very few of these Belgian “4 characters” rings can be observed nowadays.

note 1 : 

Green ring with a white 3 alpha-numeric code used in France and Belgium.

note 1 : very few of these “3 characters” rings can be observed nowadays.

note 2 : 

White ring with black 4 alpha-numeric code : T01N.

note 1: this ring is from Polish Black-headed Gull (Larus ridibundus) project.

White ring with black 4 alpha-numeric code : starting number '3'.

note 1 : a few birds of this series are ringed in Denmark.

note 2 : 

(light) Blue ring with white 3 alpha-numeric code : 1 letter (R) and 2 numbers.

note 1 : until 1999 some 145 rings have been placed from which 85 light-blue and 23 green.
note 2 : the light-blue is quick used and turns into 'white', therefore greens rings have been used since 1999. As first letter is used A, C, M, E, H, J and a second letter is used A, C, E, H, J, K, L, M, N, P, R, T, V, W, X, Y. As number is used 1 till 9, but the number 0 is not used.
note 3 : since 1999 in three other places in Germany all together 3 chicks were ringed with green rings.