I know what is external type in solidity functions but this is new to me: external auth(wallet) sometime without (wallet) argument is only displayed as external auth. What does it means? or can it be used without external? Just as auth?
auth() isn’t a standard Solidity modifier like
external, and is probably a function modifier that is specific to the contract you are inspecting. Solidity lets you create custom modifiers, e.g. the
Ownable contract in the openzeppelin-contracts library defines a custom
onlyOwner modifier, which may then be used (by itself and by extending contracts) to “mark” functions as being only callable by the contract owner.