From Qedoc

This categorisation system categorises modules by the date of their most recent file edit, which may be different from the date on which the module's page was last updated. Often the dates will be the same, but where they differ, either the module or the page may need updating. Older files may need inspection and updating anyway (e.g. to check compatibility with more recent software versions).

This list does not give an accurate idea of submission rates, as it only ever takes into account the latest version of a module file. Creation date and intermediate updates are all ignored. Over time, older months should gradually disappear from this listing system completely. One of the uses of this page is for identifying older modules for updating.

The DPL extension (version 1.6.6) produced a SQL statement which lead to a Database error.
The reason may be an internal error of DPL or an error which you made,
especially when using DPL options like titleregexp.
Query text is:
SELECT DISTINCT `en_page`.page_namespace as page_namespace,`en_page`.page_title as page_title, REPLACE(REPLACE(CONCAT( IF(`en_page`.page_namespace=0, , CONCAT(CASE `en_page`.page_namespace WHEN 1 THEN 'Talk' WHEN 2 THEN 'User' WHEN 3 THEN 'User_talk' WHEN 4 THEN 'Qedoc' WHEN 5 THEN 'Qedoc_talk' WHEN 6 THEN 'Image' WHEN 7 THEN 'Image_talk' WHEN 8 THEN 'MediaWiki' WHEN 9 THEN 'MediaWiki_talk' WHEN 10 THEN 'Template' WHEN 11 THEN 'Template_talk' WHEN 12 THEN 'Help' WHEN 13 THEN 'Help_talk' WHEN 14 THEN 'Category' WHEN 15 THEN 'Category_talk' END, ':')), `en_page`.page_title), '_', ' '),'♣','⣣') as sortkey, `en_page`.page_counter as page_counter FROM `en_page` INNER JOIN `en_categorylinks` AS cl0 ON `en_page`.page_id=cl0.cl_from AND (cl0.cl_to='Modules_by_last_file_edit_date') WHERE 1=1 AND `en_page`.page_namespace IN ('14') AND `en_page`.page_is_redirect=0 ORDER BY sortkey ASC LIMIT 0, 100

Error message is:
Illegal mix of collations (latin1_bin,IMPLICIT), (utf8_general_ci,COERCIBLE), (utf8_general_ci,COERCIBLE) for operation 'replace' (localhost)