An important distinction between PubMed and Crossref is the level of curation that the two organizations undertake of the data submitted. Crossref explicitly relies on the accuracy of publisher-submitted metadata, whereas PubMed carries out extensive internal QA, and unfortunately this means that the level of accuracy of Crossref records is not as high as it is for PubMed. Because of this distinction, eXtyles is more likely to insert a warning about differences between submitted references and Crossref, whereas it is biased more towards correction of differences against PubMed.
To check the accuracy of a reference in the PubMed and Crossref databases, click on the PubMed or DOI link that is returned with the reference. If you come across a record in PubMed that contains verifiable errors in comparison with the published article, you should contact PubMed Help. If you come across an error in the Crossref database, you should contact Crossref Support.