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.
PDF is not like HTML where you can apply formatting tags for emphasis. As you've read in the PDF reference, all that you do in PDF is to setup a graphics environment (colours used, fonts used, etc) and then put text on the page.
If you want to have something show in bold, use a font that is bold. If you want to have something show in italic, use a font that is italic.
Older software used dirty tricks to create "bold-alike" text, but the good (and easy) way to do it is to make sure you select the correct font before you start drawing text.