I don’t need this right now, but how do I remove an order which does not fit the inventory? I can’t buy from myself and if I just cancel it, all items that don’t fit are lost. In theory, I could ask someone to buy such order in parts, but that’s a complicated workaround. Looks like such sales are uncancellable for the most part.
Stuff you upload in the internet is infinite.
Stuff you download is finite due your harddisk 
So either we set a max. item amount what would be sad or we implement something like
"ti:stop:ID:AMOUNT".
Or you return the ability to buy your own orders… I don’t see what was wrong with that in the first place.
Free OCD for everyone
It’s not like you can’t do that with current model. Just set the price ridiculously high and change it to very low before taking the order down to prevent tax expenses.
And keep several orders of the same item for each of them to fit in the inventory. It’s easy if you don’t care about actually selling it.