This is a tracking category. It is used to build and maintain lists of pages—primarily for the sake of the lists themselves and their use in article and category maintenance. It is not part of the encyclopedia's categorization scheme. More information: This category is hidden on its member pages—unless the corresponding user preference is set. These categories are used to track, build and organize lists of pages needing "attention en masse" (for example, pages using deprecated syntax), or that may need to be edited at someone's earliest convenience. These categories also serve to aggregate members of several lists or sub-categories into a larger, more efficient list (discriminated by classifications).

Administrators: Please do not delete this category even if it is empty! This category may be empty occasionally or even most of the time.

Pages are added to this category by pages and templates that use ((ISBN)) and ((ISBNT)).

In these templates, ISBN parameters are checked for invalid ISBNs They are also checked for text that shouldn't be there, including "ISBN", "N/A", "none", dashes (use hyphens instead), lower-case "x" (use "X" instead), and tab characters.

Error messages for bad ISBNs look like one of these: