Sources of Auto-Propagated Metadata

Component

Some components have metadata templates assigned to their ports. The metadata from templates propagates from the component to the connected edge.

For example, metadata for error records are auto-propagated on the second output port of SpreadsheetDataReader:

Metadata propagated from the component, metadata template is defined within the component:

Edge

Some components (e.g. SimpleCopy) propagate metadata from input to output ports. Thus metadata can be auto-propagated on an edge as coming from a different edge, even several components away.
Metadata propagated from the another edge:

Metadata propagated from a distant edge:

Advanced metadata propagation - DataIntersection:

Metadata can be propagated from left to right or from right to left. Some components can propagate metadata between ports at the same side of the component using the port on the other side. Components not changing the metadata structure (e.g. Filter, SimpleCopy, etc.) usually propagate metadata from both sides.

The component-specific metadata propagation details can be found in the reference of particular components.