elasticsearch/docs/reference/elasticsearch-plugins/mapper-plugins.md

mapped_pages
https://www.elastic.co/guide/en/elasticsearch/plugins/current/mapper.html

Mapper plugins [mapper]

Mapper plugins allow new field data types to be added to Elasticsearch.

Core mapper plugins [_core_mapper_plugins]

The core mapper plugins are:

Mapper size plugin

The mapper-size plugin provides the _size metadata field which, when enabled, indexes the size in bytes of the original _source field.

Mapper murmur3 plugin

The mapper-murmur3 plugin allows hashes to be computed at index-time and stored in the index for later use with the cardinality aggregation.

Mapper annotated text plugin

The annotated text plugin provides the ability to index text that is a combination of free-text and special markup that is typically used to identify items of interest such as people or organisations (see NER or Named Entity Recognition tools).