It's not. Take for example the pushbutton switch on the arduino uno - it has a very specific one-of-a-kind footprint. So if you don't have the mfg part number

It's not. Take for example the pushbutton switch on the arduino uno - it has a very specific one-of-a-kind footprint. So if you don't have the mfg part number, there's no way to populate the PCB. You're literally going to have to re-layout the board and choose your own. And what if the debouncing of the new switch is different than the original and doesn't work with their firmware. Providing the mfg for ALL the part numbers is critical in hardware design. In a lot of cases, where hardware is mission critical (like space or medial), if one single mfg part number changes or the source manufacuture changes, the entire system needs to be requalified/tested because of the larger ramifications. If you start willy-nilly grabbing parts off the shelf that might work, you're going to eventually get burned. My request is simple - if you're publishing an open source projet, please publish the offical BOM that the platform was validated under, and put the BOM in source control should a part become discontinued and need a replacement. This is standard for any hardware product. Edit: The switch mfg part number is actually a real problem. See this person who tried to reverse engineer the part number. Notice the ??? in the mfg? Google doesn't return much with that part number. If you can find the actual mfg datasheet for that part number I'd love to know. I have no idea where to order that switch. http://mburdis.com/BOM_Ardiuno_UNO_Rev3.html http://mburdis.com/BOM_Ardiuno_UNO_Rev3.html