--- title: Indexing pipeline extensions (IPEs) for Smart Snippets content slug: m5bf8282 canonical_url: https://docs.coveo.com/en/m5bf8282/ collection: leverage-machine-learning source_format: adoc --- # Indexing pipeline extensions (IPEs) for Smart Snippets content This section lists the [indexing pipeline extension (IPE)](https://docs.coveo.com/en/206/) samples that let you modify the [items](https://docs.coveo.com/en/210/) that must be used by a [Coveo ML](https://docs.coveo.com/en/188/) [Smart Snippet](https://docs.coveo.com/en/laea5490/) [model](https://docs.coveo.com/en/1012/). These IPEs modify existing [index](https://docs.coveo.com/en/204/) content to add [Google structured data](https://developers.google.com/search/docs/data-types/faqpage) in JSON-LD format within the `` of the HTML items that must be used by the model to extract content. ## IPE scoping CSS selectors This [IPE](https://docs.coveo.com/en/lc6d0080/) lets you specify CSS selectors that represent questions and answers in an HTML item. When CSS selectors are specified to identify questions and answers, this IPE uses these selectors to create JSON-LD structured content and add the rendering to the `` of the HTML item. ## IPE scoping index fields This [IPE](https://docs.coveo.com/en/m52a0468/) lets you specify index fields containing the questions and answers you want the model to use, and convert this content to JSON-LD format, which will be added in the `` of the HTML item.