All 3 Uses of

protocol
in
Nineteen Minutes

Later today, there would be a ceremony to honor the memories of those who'd died here a year ago, but because Patrick had been involved in the new security protocols for the school, he'd been able to sneak Alex in for an advance viewing.†
Chpt 2

Definition:

rules; or the way something is typically done

The exact meaning of porous can depend upon its context. For example:

"diplomatic protocol" -- standard procedures followed by diplomats
"The Kyoto protocol to reduce greenhouse gases" -- a formal written agreement between countries
"computer communications protocol" -- technical specifications that describe rules that enable computers to communicate
"research protocol" -- rules or procedures followed during a research project such as a medical trial
"concussion protocol" -- rules or procedures followed after an athlete has a concussion
"business protocol" -- standard etiquette or conventions practiced in business