How does phpBB theme display work?

Question

PHP

<tr>
      <th>{L_AUTHOR}</th>
      <th>{L_MESSAGE}</th>
    </tr>

The point is that the above code displays a message in the topic. But where to dig further? Where is L_MESSAGE laid down? Where is the mysql query from the database? In what file?

Answer 1

Such tags are declared in function files

Answer 2

variables starting with L_ are language
variables, this variable is specified in the file /language/en/common.php