wp-includes/pomo/entry.php:97Generates a unique key for this entry.
string|false public function key() { if ( null === $this->singular ) { return false; } // Prepend context and EOT, like in MO files. $key = ! $this->context ? $this->singular : $this->context . "\4" . $this->singular; // Standardize on \n line endings. $key = str_replace( array( "\r\n", "\r" ), "\n", $key ); return $key; }Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/pomo/entry.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.