Functions arguments, returned parameters and watched variables are reported in the same section for each function call. The trace is available as an array, or can be displayed or written in a file. Traced variables can be processed by provided user functions for displaying purposes.
This package is not a replacement for full fledged PHP debuggers. It is useful for (1) remote debugging, (2) to debug a complex sequence of function calls, (3) to display non text variables in a user readable format.
Remote debugging is sometimes the only option to debug a package that works fine on your system, e.g. a 32-bit OS, but breaks on a different system, e.g. a 64-bit OS, which you have no access to. A remote user who has the latter OS could run the package, then send you the trace for analysis.
It is sometimes difficult not to loose track of functions calls in some live debugging sessions even with top notch PHP editor/debuggers. The trace produced by this package may come handy and is easy to use in combination with the source code to track calls and variables.
Some variables native format does not always display well, typically: packed data and UTF-8 strings. They can be converted as they are being traced to a readable format by provided user functions. For example: converting binary strings to hexadecimal, or UTF-8 string to Unicode.