In order to export a .csv file showing the Stock Parts currently being used, you will need to do the following:
Go in the General Tab
Click Export Manager
Click Stock
Click Stocked Parts
Click Stocked Parts Details, if you wish you can tick/untick the 'Open Export File' at this step
Choose where you would like the file to be saved, then click OK
Choose your preferences - make sure that in the Part Status box you type 'Active'
Click Export
Choose the preferred Fields, again making sure Part Status is selected, then OK
Once this is done, if you've chosen the 'Open Export File' option, the .csv file will generate and open, otherwise it will be saved in the location you've chosen.
