When using the "MetaData" key, what must the FORMAT value be prefixed by?

In the context of Splunk, the FORMAT value for the "MetaData" key must be prefixed by "sourcetype::". This prefix is essential because it specifically indicates the type of data that is being referenced or categorized within Splunk. The "sourcetype" is a fundamental part of Splunk's data indexing and searching capabilities, allowing the system to understand how to interpret the incoming data.

When referencing metadata, particularly in scenarios where you are customizing data classification, using the "sourcetype" prefix ensures that the specified format aligns with Splunk's expectations for handling and indexing the data correctly. Each "sourcetype" corresponds to a defined data structure, which tells Splunk how to parse and process that data during searching and reporting.

The other options, while they represent various identifiers used in Splunk (such as host, source, or index), do not serve the same purpose in the context of the FORMAT value for the "MetaData" key, specifically tailored for defining how Splunk interprets the data type involved. Each of these identifiers has its own significance in indexing and searching but does not apply to the "MetaData" key's FORMAT value in the same manner as "sourcetype