Source

File: wp-includes/class-wp-theme.php

public function offsetGet( $offset ) {
		switch ( $offset ) {
			case 'Name':
			case 'Title':
				/*
				 * See note above about using translated data. get() is not ideal.
				 * It is only for backward compatibility. Use display().
				 */
				return $this->get( 'Name' );
			case 'Author':
				return $this->display( 'Author' );
			case 'Author Name':
				return $this->display( 'Author', false );
			case 'Author URI':
				return $this->display( 'AuthorURI' );
			case 'Description':
				return $this->display( 'Description' );
			case 'Version':
			case 'Status':
				return $this->get( $offset );
			case 'Template':
				return $this->get_template();
			case 'Stylesheet':
				return $this->get_stylesheet();
			case 'Template Files':
				return $this->get_files( 'php', 1, true );
			case 'Stylesheet Files':
				return $this->get_files( 'css', 0, false );
			case 'Template Dir':
				return $this->get_template_directory();
			case 'Stylesheet Dir':
				return $this->get_stylesheet_directory();
			case 'Screenshot':
				return $this->get_screenshot( 'relative' );
			case 'Tags':
				return $this->get( 'Tags' );
			case 'Theme Root':
				return $this->get_theme_root();
			case 'Theme Root URI':
				return $this->get_theme_root_uri();
			case 'Parent Theme':
				return $this->parent() ? $this->parent()->get( 'Name' ) : '';
			default:
				return null;
		}
	}