Expert signature ?

Hi !

I find same mark on different stamps. Did you know what can be this ? Expert signature ?
Every stamps I get with this sign are semi modern or modern. Thanks you !

[Πρέπει να είστε εγγεγραμμένοι και συνδεδεμένοι για να δείτε αυτόν το σύνδεσμο.]

So, I concluded from this silence that expert is totally unknow or forgetten ! 

Elboiteu έγραψε:So, I concluded from this silence that expert is totally unknow or forgetten ! 

Personally, for the first time see such signature
Maybe because I collect classical Greece and in the period 1924-today I have the basics, and I have not studied them well ...