itemref This is a space seperated list of IDs of elements which are not descendants of the element on which it appears. It identifies each element whose ID it includes as defining a property of the item on which it is present. The itemref attribute must not be specified on elements that do not have an itemscope attribute. Content models This section changes the content models defined by HTML in the following ways:
Inventive tools of the artist's trade also produced advances in creativity. Impressionist painting became possible because of newly invented collapsible, resealable metal paint tubes that facilitated spontaneous painting outdoors. [ citation needed ] Inventions originally created in the form of artwork can also develop other uses, ., Alexander Calder's mobile, which is now commonly used over babies' cribs. Funds generated from patents on inventions in art, design and architecture can support the realization of the invention or other creative work. Frédéric Auguste Bartholdi 's 1879 design patent on the Statue of Liberty helped fund the famous statue because it covered small replicas, including those sold as souvenirs. 
Speaking about the difference between Standard and extended marking. In many cases, marking, in turn is mirrored into the order line. Say – in purchase line you have three fields – Reference Type, Reference Id and Reference Lot. They can point to production BOM Line or sales order line for which the purchase line is intended. In Standard marking mode these fields are set ONLY if marking is made for full quantity (like 20 pieces in purchase line and full 20 pieces are marked). In extended mode these fields are set even if marking is made for partial quantity. (Do not ask me what will happen if you mark inventTrans to several different inventTrans. Perhaps, it will set reference fields in source order to the last target inventory transactions)…
I do not have too much experienc with Decrease action setting, you mentioned. I am only sure that firming is totally independent from the planning itself. Firming only takes planned order (or chain of planned orders in case of nested productions), and create orders for them. It does not check anything in actions messages.