| Code | Display | Definition |
| abstract | Abstract | The URL will reach a brief summary for the article. |
| full-text | Full-Text | The URL will reach the full-text of the article. |
| supplement | Supplement | The URL will reach a supplement, appendix, or additional supporting information for the article. |
| webpage | Webpage | The URL will reach a webpage related to the article, where the content is not easily classified as abstract, full-text or supplement. |
| file-directory | File directory | The URL will reach a file directory. |
| code-repository | Code repository | File archive and web hosting facility for source code of software, documentation, web pages, and other works. |
| restricted | Restricted | The URL content has restricted access (e.g. subcription required). |
| compressed-file | Compressed file | Compressed archive file (e.g. a zip file) that contains multiple files |
| doi-based | DOI Based | The URL is derived from the Digital Object Identifier (DOI). |
| pdf | PDF | The URL will reach content in PDF form. |
| json | JSON | The URL will reach content in JSON format. |
| xml | XML | The URL will reach content in XML format. |
| version-specific | Version Specific | The URL will reach content that is a specific version of the article. |
| computable-resource | Computable resource | The URL will reach content that is machine-interpretable. |
| not-specified | Not Specified | Used when URL classifier is not specified but expected in a system. |