| info:ark/ (xml) | Namespace for Archival Resource Keys |
| info:arxiv/ (xml) | Namespace for arXiv.org identifiers |
| info:bibcode/ (xml) | Namespace of Astrophysics Data System bibcodes |
| info:bnf/ (xml) | Namespace of identifiers used by the Bibliothèque nationale de France |
| info:ddbj-embl-genbank/ (xml) | Namespace of identifiers for sequence records in DDBJ/EMBL/GenBank |
| info:dlf/ (xml) | Namespace of Digital Library Federation Identifiers |
| info:doi/ (xml) | Namespace of Digital Object Identifiers |
| info:eu-repo/ (xml) | Namespace of identifiers used by the European Repository Systems for describing semantic relationships in Compound and Complex documents. |
| info:fedora/ (xml) | Namespace of Fedora Digital Objects and Disseminations |
| info:hdl/ (xml) | Namespace for Handles |
| info:inchi/ (xml) | Namespace for IUPAC International Chemical Identifiers (InChI) |
| info:lanl-repo/ (xml) | Namespace of identifiers used in the Repository of the LANL Research Library |
| info:lc/ (xml) | Library of Congress Identifiers |
| info:lccn/ (xml) | Namespace of Library of Congress Control Numbers |
| info:ncid/ (xml) | Namespace of NACSIS-CAT Identification Numbers |
| info:netref/ (xml) | Namespace of NISO Standard for Network Reference Services |
| info:nla/ (xml) | Namespace of identifiers for the National Library of Australia's digital & digitised collections |
| info:nyu/ (xml) | Identifiers for New York University Digital Objects |
| info:oclcnum/ (xml) | Namespace of OCLC Worldcat Control Numbers |
| info:ofi/ (xml) | Namespace of Registry Identifiers used by the NISO OpenURL Framework Registry |
| info:pmid/ (xml) | Namespace of identifiers of PubMed records |
| info:pronom/ (xml) | Namespace of PRONOM Unique Identifiers |
| info:refseq/ (xml) | Namespace of identifiers for RefSeq reference sequence record |
| info:rfa/ (xml) | Namespace for Registry Framework Architecture Identifiers (RFA) |
| info:rlgid/ (xml) | Namespace of RLG Database Record identifiers |
| info:sici/ (xml) | Namespace of Serial Item and Contribution Identifiers |
| info:sid/ (xml) | Namespace of Source Identifiers used in the NISO OpenURL Framework |
| info:srw/ (xml) | Namespace of Search/Retrieve Web Services |
| info:ugent-repo/ (xml) | Namespace of identifiers for the University Library Ghent information assets |