[Arran]

That's because Philco used to use numbers on the schematic to identify parts, which would then have to be looked up on the parts list, rather then writing the part values on the schematic itself. Fortunately they changed this practice as time went on, other companies did not, Sparton for one, in such cases I make a photo copy and then write in the values on the copy so I don't have to keep going back and forth between the schematic and the parts list.
Regards
Arran