How to store custom data into Excel cell
 

Hello experts,

I'm writing a custom add-in for Excel. I need to store some custom data
within Excel document/sheet/cell. Similar to "Web query" in Excel -
when it is put in Excel sheet, it saves information about original URL
and cells can be updated later. Similar to that, I would like to save
some other information for each of the cells I will create from my
add-in. For example: I would create 3 cells from my add-in and would
like for each of those cells to save the information about some IDs,
source of that cell (for example - file name) or anything else.
It would be enough for me if I can save my string in any of the
properties of Cell/Document/Sheet. It would be good enough to save it
in a document or sheet because I can save it in XML or some other
format and later deserialize it. What is important to me is that
information have to be saved when user saves document and have to be
available to my application when document is open next time.

Is there anyone who know how this can be done? Which property can be
used or can I use my custom class as a Cell property?

Thanks in advance,
Sasa