Advanced node scoping using named selections with DPF-Post

Hello,
I was wondering whether there is any possibility for some kind of advanced node scoping using named selections in DPF-Post.
For instance I have got a certain named selection inside my .rst-file which I want to use as a scoping with the additional restriction to only use its corner nodes, like one would do it in MAPDL:
```
CMSEL, S, NODE_SELECTION
NSLE, R, CORNER
```
Or if you only have got some kind of element named selection and want to work on its exterior corner nodes for instance:
```
CMSEL, S, ELEMENT_SELECTION
NSLE, S, CORNER
NSEL, R, EXT
```

Is there any way to perform this kind of filtering when browsing result data like stresses using DPF-post?

Any help is very much appeciated.

Start by reviewing DPF-Post's named-selection and result-browsing entry points for data from an .rst file. Determine whether scoping can be restricted to corner nodes or exterior corner nodes, and treat support for the requested MAPDL-style filters as done when stresses can be browsed over those filtered scopes.

Written by the indexing model from the issue text.