The is defined in class PntSite, but can be overriden by setting the debugMode field of the Site object. The following values are recognized: '', 'short', 'verbose'.
The easiest way to set the debug mode for all applications is to edit the class Site and use the code from the comment with the var $debugMode override.
If you want to set debugMode for a single application we advise to edit the index.php of the application and add a line like $site->debugMode = 'verbose'; immediately after the line that assigns a new Site to $site. An example of this can be found in example6.
For what the debug mode does, see . For information on how phpPeanuts handles errors and (does not) print informative error messages, see how to hande E_USER_WARNING and E_USER_ERROR.
TIP: Since 1.2, when you are debugging you can output a backtrace even if there is no error by calling pntPrintBacktrace(debug_backtrace());