Getting information about item (inside bag, or at bank)

[Baertram]

Hi there,

i'm totally new to LUA but I think I understood how it works so far.
I tried some smaller code lines and read other bigger addons to understand, how LUA works with ESO.

Currently I try to find out, how I can see, if an item is inside my inventory or only at my bank.
I'll see this already, if I open the research tab at a craft station e.g. But it will only sho inside the tooltip of the item (at the top right edge of the tooltip).
I#d like to check this for every icon shown in the research item's list.

Is there any function in the API which returns this information for me, without having to mouseover an item and check the tooltip? I did not find any so far.
I only saw there is a global variable BAG which will indicate me BAG_BANK e.g. as a value. But I'm not sure if I can use this variable somehow and if this is the information I'm searching for.

I appreciate every help I can get.

Thank you.