The size of the properties of a STAC item can greatly impact it's usefulness and searchability.
On one hand, having the smallest set of useful metadata for search and indexing helps keep search indices performant and limits the size of the index as a collection grows.
On the other hand, when additional useful metadata is available in a difficult or tedious to parse form (XML for example), deferring the parsing of the metadata to the consumer can greatly increase the effort required to make use of the data.
This dichotomy presents the need for an additional metadata container which will allows for producers to pre-parse potentially useful metadata while avoiding a set of item properties that becomes too large to manage.
The STAC item extended metadata object seeks to solve this by standardizing a structure that can contain the extended metadata in JSON format and be provided as an asset within an item.
The motivating work for this can be found in [this PR to stactools](https: