The “unit records” here, unlike those in the Memex example, are generally scraps of typed or handwritten text on IBM-card sized edge-notchable cards. These represent little “kernels” of data, thought, fact, consideration concepts, ideas, worries, etc., that are relevant to a given problem… Each such specific problem area has its notecards kept in a separate deck, and for each such deck there is a master card with descriptors associated with individual holes about the periphery of the card. There is a field of holes reserved for notch coding the serial number of a reference from which the note on a card may have been taken, or the serial number corresponding to an individual from whom the information came directly (including a code for myself, for self-generated thoughts).
Even Doug Englebart was thinking about how to distinguish between the thoughts of others and thoughts he had generated himself.