title: How to bold a text in PDF?
body: <p>I'm developing a new function to "my" program. This function is able to write PDF files by the simple way, making a simple text file with some codes of PDF standard.</p>
  
  <p>I'm trying to understand how it works yet, but my first problem is about how to apply bold on some line of my document.</p>
  
  <p>I've already downloaded the PDF REFERENCES GUIDE, but I've not found nothing about it.</p>
  
  <p>Any idea? </p>