Whoa, hold it. Ipc2581 is a complex beastie.
Here is the problem that 2581 tries to solve.
We have schematics , stored in some proprietary format dpeneding on cad tool. This schematic references to components that will have to be bought somewhere. Modern cad tools link to procurement tools... The schematic may have additional pointers for layout. Like : this is differential pair , that is controlled impedance at 65 ohms. The link schematic to pcb is through a netlist. That netlist only ports over layout relevant info .. Who actually makes the resistor or where we buy it is irrelevant for the pcb layouter. And then the pcb tool spits out gerber. Further down the pipe it would be interesting for the bare board tester to have the netlist as opposed to have to extract it ( this is what odb++ solved ). Now we get into pcb assembling. We need info about part values. Pick and place files solve this only to an extent. For full cycle control you need to dig and scratch for more info.
Different software tools use intermediate file formats to do data exchange. And every cad vendor has his own. Move on to electrical testing and rework. It becomes an even bigger hairball. Test fails. Turns out a vishay part was placed instead of a tdk ... What was specced in schematic ? Was it overruled by the beancounters ? I s there a design variant ? Paperwork paperwork and intermediate files.... Coming for. Different tools , only exchanging partial info and leavingit up to the humans to 'glue it together' and p,ay sherlock holmes.
That is what 2581 attempts to solve. 1 format that holds ALL information about a board assembly. From part procurement , electrical interconnect, rules , everything. Using this 1 dataset you can get an anser to any question you have at any given point in the flow from schematic concept to a packaged , tested and ready to ship board.
No more need for intermediate files , no more data lost 'in translation'...
Note that 2581 does not hold the actual schematic , nor is it a fileformat to story polygons and tracks that make up a pcb layout. It is a database that tells you there is a part from vishay , this prtnumber, procured from this vendor , that has pin 1 connected using a 60 phm controlled impedance line that originates at coordinates so and so and terminates at coordinates such and such. The value of the part is 1nf with this tolerance. The part sits at coordinates so and so with this alignment.
Using this single dataset the bare board testers, the pick and place robots, the final board testers and any other machine or step required in the actual production of the board ( from the guy picking the prepreg and copper foils and needing to know the thicknesses of each to the final machine that verifies all parts are soldered down and the board powers up) have access to the data they need, and they also have the relation of that data to other data. You can extract pick and place data fro. This file , you can extract gerber from this file , you can extract netlist , bill of materials and many other things from this single file. The only thing not in there is probably what that component symbol looks like on the screen and its coordinates, so you can't extract the schematic . Although i think they even provisioned for that...
That is the attempt.
Note that they have been at it for at least a decade .... And we need to see the first tools that are feature complete....