What is the relationship among the following article reference numbers: PMCID, NIHMSID, and PMID? The PMCID is a unique reference number or identifier that is assigned to every article that is accepted into PMC. The PMCID is also used by recipients of NIH funding to demonstrate compliance with the NIH Public Access policy. The PMCID can be found in both PMC and PubMed. The NIHMSID is a preliminary article identifier that applies only to manuscripts deposited through the NIHMS system. The NIHMSID is only valid for compliance reporting for 90 days after the publication date of an article. Once the Web version of the NIHMS submission is approved for inclusion in PMC and the corresponding citation is in PubMed, the article will also be assigned a PMCID. The PMID is a unique reference number for PubMed citations. The PMID is a distinctly different number from the PMCID and is used only for PubMed records.

PubMed PubMed - Major Topic Clinical Queries NLM MeSH Browser

In addition to the comprehensive journal selection process, what sets MEDLINE apart from the rest of PubMed is the added value of using the NLM controlled vocabulary, Medical Subject Headings (MeSH®), to index citations.

MEDLINE is the largest subset of PubMed

PubMed citations are created for content not already in the MEDLINE database. Some PMC content, such as book reviews, is not cited in PubMed.

Science is cumulative. But to be truly cumulative, we need to be able to read and understand what has come before us. And this comes down to an issue of access.