With Powerpoint, as I see it you have a Slide Master, which contains the immutable content that each slide you create contains. Here you would put headers and logos etc.
Then you have layouts, that contain placeholders that you can choose for each slide.
You can't put a placeholder on a slide master.
What I would like to do is have a placeholder that is common all layouts, but only needs to be edited once.
An example of this might be a customer presentation, where you have a skeleton presentation with a header slide with placeholders specific to the customer, then a series of content slides.
I'd like users to be able to edit the header in a content slide (say with the customer name) and have that change reflected to all slides that share the same master.
So kind of like half way between the fixed content in a master, and the per-slide placeholders in a layout.
Is it possible? It would be useful, because then users would never need to edit the masters.