A file with .enl extension is a data file created with Clarivate EndNote application to store a collection of citations. The citations contain information like the title of work, author, publish date, journal or conference information, year of publishing, and other reference material. EndNote is used for managing bibliographies along with creating citations. ENL files may also include links to the citations for viewing online or downloading as PDF document if available. EndNote uses ENL as the default file format for saving files.
ENL File Format - More Information
ENL files are stored as binary files without the availability of any details about the internal file format. However, with EndNote 8 and later, a .Data folder is saved alongside the ENL file that contains the library data structure for the contents inside the ENL file. This .Data folder needs to be moved in case the ENL file is moved from one location to another. Prior to EndNote 7, this folder contains images and other objects that are inserted into the Image field of a reference.