This is a tracking category for CS1 citations that have URI scheme errors.

Help desk

External links in Citation Style 1 and Citation Style 2 templates are made from two parts: the title (|title=, |chapter=, etc.) and the URL (|url=, |archive-url=, |chapter-url=, etc.). The |url= parameter and other URL parameters must begin with a supported URI scheme. The URI schemes http://, https://, and the protocol relative scheme // are most commonly used; irc://, ircs://, ftp://, news:, mailto: and gopher:// are also supported.

The URL scheme and host are checked to ensure that they contain only Latin characters, certain (required) punctuation, and do not contain spaces. The URL may be protocol relative (begins with //). If there are no spaces and the URL is not protocol relative, then the scheme must comply with RFC 3986.^[1]

Some URL domains are written with non-Latin characters. cs1|2 does not accept those kinds of URLs so they must be 'internationalized'. Online tools are available to internationalize URLs that are written in non-Latin scripts:

• "IDN Conversion Tool". Verisign.

Top- and second-level domain names are checked for proper form. Generally, top-level domain names must be two or more letters; second-level domain names must be two or more letters, digits, or hyphens (first and last character must be a letter or digit). Single-letter second-level domains are supported for:

• all cc TLDs (the country code is not validated)
• the .org TLD
• certain letters of the .com TLD (q, x, z)
• certain letters of the .net TLD (i, q)
• certain other TLDs (.cash, .company, .foundation, .org, .today)

Third- and subsequent-level domain names are not checked. The path portion of the URL is not checked.

There is an additional test for |archive-url=. The cs1|2 templates expect that |archive-url= will hold a unique URL for an archived snapshot of the source identified by |url= or |chapter-url= (or any of its aliases). This error message is emitted when the value assigned to |archive-url= is the same as the matching title or chapter URL.

To resolve this error, ensure that:

• |url= and other URL parameters contain valid URLs
• URLs copy-pasted from elsewhere include the URI scheme
• that the domain name uses only Latin characters

Pages with this error are automatically placed in Category:CS1 errors: URL.^[a]

Notes

References