In what key in an item should I save a string of a few hundred Kb of data?

I need to save some json-data in item.
I'll stringify it to make it easier.
It could be a few hundred Kb in size.

In what key should i save it?
Preferably it should not be indexed, but when trying to save it in a key called "meta" (like in processes) to avoid it to be index I get the message "meta is not allowed". (However I get the same message when I try to save it in "value" or "myvalue", so it's not really meta that is the problem.)

At https://support.onify.co/docs/items#indexing-items it says
"The maximum size for an item is 100 mb and for attributes it is 32 Kb."

As an attribute I can save it as whatever key name I want, but then it will be limited to 32Kb.

Going through the keys in Swagger at
/documentation#/admin/postAdminItems
I can't really find a suitable key to use.

Even though I successfully tried saving 300Kb of random data in the key "description", that is not what it is supposed to handle. :)

So please advice in what key I could save "up to 100 mb of data".