The _content field in Lucene for Sitecore is basically the full text index. If you index things like PDFs, Word documents, etc., then the results of the IFilter get stored in the _content field.
You can add computed fields into the _content field simply by specifying them with the name ‘_content’. However, I found some differences with how patch files behave. Continue reading “Appending to the _content field in Sitecore Search 7.2 and 7.5”