wp-admin/includes/meta-boxes.php:745Displays post excerpt form fields.
$postWP_Postfunction post_excerpt_meta_box( $post ) { ?><label class="screen-reader-text" for="excerpt"> <?php /* translators: Hidden accessibility text. */ _e( 'Excerpt' ); ?></label><textarea rows="1" cols="40" name="excerpt" id="excerpt"><?php echo $post->post_excerpt; // textarea_escaped ?></textarea><p> <?php printf( /* translators: %s: Documentation URL. */ __( 'Excerpts are optional hand-crafted summaries of your content that can be used in your theme. <a href="%s">Learn more about manual excerpts</a>.' ), __( 'https://wordpress.org/documentation/article/what-is-an-excerpt-classic-editor/' ) ); ?></p> <?php}Introduced in 2.6.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/meta-boxes.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.