Records can be added to your library by importing PDF files that have a Digital Object Identifier (DOI) in the file metadata, or in the first two pages of the PDF. EndNote scans the PDF file first two pages of the file, conducts a search for the DOI in the PubMed and CrossRef databases, adds the reference data to a new library record and attaches the PDF file to that record.
The PDF file must have a DOI and you need to have access to the Internet.
If EndNote is unable to locate a matching reference, the PDF file will be added to a new record, with the filename included in the Title field. The filename will be enclosed in angle brackets, e.g. <filename.pdf>. In which case you can manually edit the record, to include the correct details.
If you edit the record and add key data such as the Authors name, Title, Year and DOI, you may then be able to obtain a complete record, using Find reference updates option.