constant-visibility.php

<?php
class Blog
{
    const BLOG_NAME = 'LibreByte';
    protected const START_DATE = '01-01-2007';
    private const CREATOR = 'sedlav';
}

class Page extends Blog
{
    public static function printDetails()
    {
        echo "Blog name: ", self::BLOG_NAME, nl2br("\n");
        echo "Blog start date: ", self::START_DATE, nl2br("\n");
        echo "Blog creator: ", self::CREATOR, nl2br("\n");
    }
}

Page::printDetails();