I have PHP application that is completely procedural (No PHP Classes). In my case, is there any formal diagrams I can draw to show how my web application that is equivalent to a UML class diagram for OOP based applications.

Thanks all
['https://Stackoverflow.com/questions/681226', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/51649/']
[doxygen](http://www.doxygen.org/) can generate call- and caller graphs automatically - if that suits your needs.
You could make some Hatley-Pirbhai models:

<http://en.wikipedia.org/wiki/Hatley-Pirbhai_modeling>