PDFEditor have support for scripting. Evey item in menu (or toolbar) runs a script (mostly just short call of function, but using complex scripts from menu is possible), and also user can type script commands directly into commandline. Every invocation of script from menu will echo the command to the commandline, so user can learn how to do things in menu directly from commandline if he wants.
QSA is used for scripting, which is based on ECMAScript standard (if you don't know what ECMAScript is, it is basically the same syntax as JavaScript)
This documentation will not explain the language syntax, but will document all functions and objects that are exported from the application to the scripting engine so they may be used in scripts and menus. Also how the scripting work in general and how it can be configured will be explained.