[speed_spread]

In JSON I often end up recreating XML attributes equivalent for metadata fields and using custom prefixes to differentiate those fields from actual data. I find it's nice the data/metadata separation at the language level.

[Ajedi32]

Can you give an example of metadata you would put in a config file that isn't configuration and isn't a comment?

[speed_spread]

Metadata is less useful in a config file since it's all static data. But for something more dynamic (messaging, persistence) attributes can be used for Time-To-Live, object class, source, signature, etc.