wp-content/themes/twentysixteen/functions.php:293Registers a widget area.
function twentysixteen_widgets_init() { register_sidebar( array( 'name' => __( 'Sidebar', 'twentysixteen' ), 'id' => 'sidebar-1', 'description' => __( 'Add widgets here to appear in your sidebar.', 'twentysixteen' ), 'before_widget' => '<section id="%1$s" class="widget %2$s">', 'after_widget' => '</section>', 'before_title' => '<h2 class="widget-title">', 'after_title' => '</h2>', ) ); register_sidebar( array( 'name' => __( 'Content Bottom 1', 'twentysixteen' ), 'id' => 'sidebar-2', 'description' => __( 'Appears at the bottom of the content on posts and pages.', 'twentysixteen' ), 'before_widget' => '<section id="%1$s" class="widget %2$s">', 'after_widget' => '</section>', 'before_title' => '<h2 class="widget-title">', 'after_title' => '</h2>', ) ); register_sidebar( array( 'name' => __( 'Content Bottom 2', 'twentysixteen' ), 'id' => 'sidebar-3', 'description' => __( 'Appears at the bottom of the content on posts and pages.', 'twentysixteen' ), 'before_widget' => '<section id="%1$s" class="widget %2$s">', 'after_widget' => '</section>', 'before_title' => '<h2 class="widget-title">', 'after_title' => '</h2>', ) );}Introduced in Twenty Sixteen 1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-content/themes/twentysixteen/functions.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.