Multi-line comments start with /* and end with */. : Introduction « PL SQL Programming « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. PL SQL Programming
3. Introduction

These delimiters may span as many lines as needed. An example is shown here:

declare
/* This code is written by java2s.com. Dec 20 2007 */
    ...
begin
    ...
end;