Mockup:
What does it mean? 50% of production capacity goes into the production of axes. The other 50% of production capacity goes into the production of lances and bows. There are 12 bows ordered (1 is currently in production).
What happens when you press '+' or '-'? In case the '%' is visible, it means that the values are skipped through: 0%, 25%, 33%, 50%, 66%, 75% and 100% (debatable). It checks whether total of all percentage orders is not higher than 100%. In the case a total of 100% is reached, all other order amounts are displayed in a dark-gray font, indicating it won't be produced at all. Same applies for 0% label. Whenever one wishes to increase one type of production above 100%, other jobs that are in percentual mode will decrease.
How do you switch between '%' and absolute orders? By pressing the icon of '%' or it's empty square. Default mode: the same as the old version (i.e. sequential production), and no '%' is shown.
Debate is possible on the exact mechanics. But I think that whenever one has no absolute orders and only percentages, it will be scaled up to 100% production, and the interface will reflect this accordingly. E.g. after all longbows are produced, it will display 100% axes-0 lances-0 longbows. Whenever one has a 100% production total, and one wishes to enter an absolute amount, the 100% will be reduced to 50% to accomodate the expectance of producing atleast the absolute amount.
P.S. The icons of the weapons still fit: