I want to create a Photoshop plug in. I recently downloaded an ICO plug in (iconformat.8bi) that saves the file as an icon. I thought it was just psp's action script file with the extension changed. But when I opened it in notepad I found that it was full of garbage with the words "this program cannot be opened in DOS mode".
So it's a program... I googled for 'creating adobe Photoshop plug in'. But it returns tons of psp tutorial sites where you can download plug-ins; NOT create them.
Does someone know where I can find the specifications for the structure of the program or a library (like scrnsave.lib for making screen savers the easy way), which helps you make it?

P.S.
My version of Photoshop is an old 7 and adobe's site is filled with CS thingies.
The Photoshop help file says that in order to create a plug-in module, I have to contact adobe developer support (I'm not intending to do this professionally or any thing. just to create a simple raw file format for one of my apps, so that I can paint and directly save to that format from psp, and may be actually convert some of my fractal generating programs into plug-ins just for fun).