Edge Specification

Event Types

The event type is a custom type to be logged.

Signature

<event_field_signature> ::= <ident> ":" ( "indexed" "<" <type_signature> ">" | <type_signature> ) ;

<event_signature> ::=
    ["anon"] "event" "{" [<event_field_signature> ("," <event_field_signature>)* [","]] "}" ;

Dependencies:

• <ident>
• <type_signature>

The <event_field_signature> is an optional "anon" word, followed by "event", followed by either a type signature or a type signature delimited by angle brackets and prefixed with "indexed".

Semantics

The event type is assigned an identifier the same way other types are assigned an identifier. The EVM allows up to four topics, therefore if "anon" is used, the event may contain four "indexed" values, else the event may contain three. If the event is not anonymous, the first topic follows Solidity's ABI specification. That is to say the first topic is the keccak256 hash digest of the event identifier, followed by a comma separated list of the event type names with no whitespace, delimited by parenthesis.