The content of each page on my site resides in it's own script file, but all the rendering and layout is in the common framework. Thus the content scripts in isolation are incomplete and should not be accessed directly. By changing their file extension they are not recognized by php processor, and since they are only ever included explicitly I could also disable all other kinds of direct access with .htaccess settings.
Alternatively this framework allows topic folders to be placed in other parts of server file hierarchy where the php processor can still read them for inclusion, but the internet can't see them. The same goes for other resources like images. Script ap_original serves to create a sybolic link to them as needed to make them temprarily accessible online. That's how it's done in the image above and also here with the document linked from the .pdf thumbnail here.
The symbolic links get tidied up eventually (TODO: automate that). Thus they can't be abused as public access. OTOH, files that I do want to make available I simply put in the /public folder.