Open a specific form

I hope that anyone else knows an answer to this question. I would be happy for a simple solution for this one too.

I assume aras.uiShowItem only can trigger the "Default" form.
With aras.uiShowItemEx you can at least pass if you want to add the "Default/Add/Edit" form.

If your specific Form is similar to the default one, the easiest solution is to use an "onLoad" event that shows hide the affected fields.
As alternative you could also make a classification specific Form and pass a fake classification with the call.

I personally use a solution based on this variant:

 link 

It opens an empty html page and you can manually specify the correct Form. But passing the item is a bit tricky. This one would be an overengineered solution that requires a lot of additional code so it looks like a normal form call.

In my case it was for a very specific use case, so not just a classic item call that you are looking for. I guess there are a better variants available. 

Maybe uiPopulateFormWithItemEx or something with uiShowItemInFrameEx. But I never used them in this context. If anyone knows more, please let me know!