What is blocked?

blocked meaning in Information Science terminology / glossary / dictionary is:
The status of the borrower account of a patron who is barred from checking out materials from the library, usually because fines for overdue items remain unpaid. Most electronic circulation systems are designed to automatically block a patron record under conditions prescribed by the library. Also refers to digital content which cannot be viewed from a user’s computer because online access is denied, usually by the installation of Internet filtering software. Public libraries that accept federal funding for Internet access are required by the Children’s Internet Protection Act (CIPA) to block pornographic and gambling content on computers used by minors.  


reference: ABC-CLIO