The format defines a handful of reified properties that have special meaning:
| Property | Name | Description | Required? |
|---|---|---|---|
@t |
Timestamp | An ISO 8601 timestamp | Yes |
@m |
Message | A fully-rendered message describing the event | |
@mt |
Message Template | Alternative to Message; specifies a message template over the event's properties that provides for rendering into a textual description of the event | |
@l |
Level | An implementation-specific level identifier (string or number) | Absence implies "informational" |
@x |
Exception | A language-dependent error representation potentially including backtrace | |
@i |
Event id | An implementation specific event id (string or number) | |
@r |
Renderings | If @mt includes tokens with programming-language-specific formatting, an array of pre-rendered values for each such token |
May be omitted; if present, the count of renderings must match the count of formatted tokens exactly |
@tr |
Trace id | The id of the trace that was active when the event was created, if any | |
@sp |
Span id | The id of the span that was active when the event was created, if any |
The @ sigil may be escaped at the start of a user property name by doubling, e.g. @@name denotes a property called @name.