If you are submitting a Zip or 7-zip file that contains multiple part files, you can include an "Instructions.txt" text file that includes the quantity, material and surface treatment of each part
For example:
partA.pdf part number: 500A quantity: 5 material: Plastic Acetal AF100 treatment: none partB.igs part number: 500B quantity: 1 material: Aluminium 2011-T3 treatment: clear hard anodized partX.pdf quantity: 1 material: Aluminium 6061-T6 treatment: blue anodized