Very Old Packing List Envelope

I was in a warehouse earlier this week and I saw a packing list envelope stick on the rack. I presume that the envelope is used to put the stock card for the management of inventory control of the products on the rack.

From the look of it, it must have there for a long time as there are water stain and dust on it.

This is a top loading packing list envelope when the content or documents are put into the pouch from the top.

Notice that the white release liner is still stick on the adhesive and only the top portion of the packing list envelope is stick on the rack.