Prefix “Οδός” and “Λεωφόρος” has been removed from all name tags, all over Greece. Prefix “Odos” and “Leoforos” also has been removed from all int_name tags, all over Greece.
As for the tag name:prefix its ok if someone wants to use it to add the above prefixes, but personally i still think that is useless.
Besides that, this tag is only a proposal. https://wiki.openstreetmap.org/wiki/Proposed_features/Directional_Prefix_%26_Suffix_Indication
(JayCBR said that too, and i agree with that).
Thank you.
PS. User George_ath has been notified.