php, files, character encoding???

I was about to start putting together some code for a text editor. One of its requirements is that the files that it creates, must be able to be used in utf-8 char. encoded page. Then I started to wonder if php's fwrite() is character set aware. I did some preliminary searching, but I didn't come up with any information. I just started reading up on unicode/utf-8's abilities a couple days ago, so I may be wrong in saying that php's fwrite() isn't character set aware. I guess I can still go ahead with the editor and run it's output through a 'read' editor to save it as a certain encoded file. Basically looking for thoughts/comments. Thanks Gerard