Help: CS1 errors

==<span id="bad_doi">Check |doi= value</span>==
<section begin="bad_doi_help_text" />{{help desk}}{{#invoke:Cs1 documentation support|help_text_error_messages|err_bad_doi}}

When {{cs1}} and {{cs2}} templates contain {{para|doi}}, a test is done to see if the prefix portion of the [[Digital object identifier|DOI]] value is correctly formatted and has what appears to be a valid registrant code.  A proper DOI prefix begins with the <code>10.</code> directory indicator.  The remaining portion of the prefix is a string of digits and the dot character which form the registrant code.  When the directory indicator is <code>10.</code>, the CS1|2 templates test for a valid registrant code.  Valid registrant codes:
* must be composed of digits
* must be in the range:
** 1000–9999
** 10000–49999
* may have one or more subcodes that begin with a dot followed by digits (1000.10)
* must not be 5555 (invalid/temporary/test)
Additionally, the {{para|doi}} value is checked to make sure that it does not contain spaces, en dashes, does not end with punctuation. Further validation of the DOI is not performed.

Do not include the <code><nowiki>https://doi.org/</nowiki></code> scheme and domain name from a URL. A proper {{para|doi}} value looks like {{para|doi|10.1103/PhysRevLett.80.904}}.

To resolve this error, ensure that the {{para|doi}} value is correct.

In very rare cases, publishers have released works with a DOI deviating from the standard form. If you are certain that such a non-conforming DOI truly corresponds to the published work, then you can add [[Help:Citation_Style_1#Accept-this-as-written_markup|accept-this-as-written markup]] around the identifier to suppress the error message. (Do not use this markup for DOIs, which are ''inactive'' rather than ''non-conforming''. Instead, use {{para|doi-broken-date}} for them.)

Pages with this error are automatically placed in {{#invoke:cs1 documentation support|help_text_cats|err_bad_doi|pages=yes}}.<ref group="lower-alpha" name="categories" /><section end="bad_doi_help_text" />