(X)Emacs can basically handle only one major mode. While this is fine for most applications, it is not very practicable for editing mixed HTML and PHP files, especially concerning indentation of lines.

Several possibilities exist to handle this situation :

• Multi-purpose multiple mode modes
  • MMM-mode (Multiple Major Modes) makes it possible to load several major modes at the time. It is not restricted to HTML/PHP. However, last activity on this project was back in 2004 !
  • MuMaMo (Major Multiple Modes)
• Dedicated modes
  • nXhtml mode for editing Xhtml files. Homepage