Editing Help:CS1 errors (section)

==<span id="invalid_isbn_date">ISBN / Date incompatibility</span>==
<section begin="invalid_isbn_date_help_text" />{{help desk}}
{{#invoke:Cs1 documentation support|help_text_error_messages|err_invalid_isbn_date}} – this error message hidden by default

[[ISBN]]s were created c. 1965. Books published before that date will not have been issued an ISBN. However, reissues of pre-ISBN publications <em>are</em> issued ISBNs, even barring the publication of a new edition. Consider double-checking whether the ISBN is valid before removing it.

To resolve this error:
* Remove the ISBN when citing a source published before 1965.
** If the cited edition or reissue of the book was published after 1965, ensure that {{para|date}} or {{para|year}} has the correct publication year. The reissue date is typically available by querying [[WorldCat]] with the reissue's ISBN. Adding {{para|orig-date}} may be appropriate in such cases; e.g., {{para|orig-date|1st Pub. 1929}}.

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