Hi Krzysztof,
Does this mean that vexing is constrained to whole arrays?
no, there is a 'clip' message for setting an active chunk of an array -- one can dynamically change both the current 'target' array, and an offset and length of the current chunk of it.
Ok, then the connection between vex and vasp seems to be fairly easy, at least for vasp messages referencing a single buffer (there can be more).
I'll have a closer look at the vexing lib some day next week.
best greetings, Thomas