We have to develop our first Tamino-Applications in the next weeks and because I
just for clarification: do you want to access the same doctype(s) from Appl.1 and Appl.2 ?
The simplest approach could be to have two different doctypes in the collection.
Or perhaps use the possibilities of optionality/multiplicity to model one doctype that can contain different elements (appropriate to the application which retrieves the documents).
Could you give an example of what you would need for each application?