Look, you're here. You typed in an acronym, probably because spelling out "Probabilistic context-free grammar" felt like too much of a commitment. I get it. Committing is hard. So, let's get this over with.
This isn't an article. It's a signpost pointing you from your shortcut to the actual destination. Try to keep up.
• Probabilistic context-free grammar
Still here? Fine. Since you seem to require a manual for even the simplest of digital constructs, let's break down what this page is, or more accurately, what it does. This page is a redirect, a function designed for precisely this kind of situation: pointing people who use shorthand to the fully articulated concept they were looking for. It’s a concession to efficiency, or perhaps just laziness. The universe hasn't decided yet.
The following categories are applied to this digital ghost of a page. They exist to track and monitor its function, a sort of bureaucratic afterlife for a title that no longer stands on its own.
• From an alternative name: This is the universe's polite way of saying you used a nickname. "PCFG" is a synonym, an alter ego, a convenient string of letters for the more substantial target. This redirect exists because it aligns with the naming conventions for common names, a system that graciously accommodates the vernacular to aid in searches and, I suppose, to prevent you from getting lost. And before you get any clever ideas about "fixing" things, it is emphatically not necessary to replace these redirected links with a piped link. The system is designed to handle this. It works. Don't touch it.
Should this redirect happen to be a flagrantly incorrect name for the target—a genuine error, not just a casual abbreviation—then the template {{R from incorrect name}} would be used instead. A different label for a different class of mistake.
• From a page move: This is a digital forwarding address. It signifies that a page once lived here but has since been moved, or renamed, to a better location. This redirect is the ghost it left behind, a necessary haunting to prevent the shattering of links across the digital space. Without it, every internal and external connection that pointed to the old name would simply break, leading to the kind of digital chaos that gives archivists nightmares. This is a monument to foresight.
And, for what it's worth, the system is smart enough to handle its own affairs. When it's appropriate, protection levels are automatically detected, described, and sorted into their own categories. It’s all very orderly. Now, you know where to go.