Factory dialogue: Input Storage / ???? / Maximum input storage.

[benjad]

Ok, I remember this being added, but can't find the announcement, and it hasn't made it to the help yet.

In the factory dialogue, in the consumption line.    the three values with the slashes.  the first is input storage, the last is max storage, what is the middle value?   

[HDomos]

It shows the number of goods on the way to the factory