Extend the model of this Exchange type.
Material contributions can be in the form of
giving something
borrowing
Giving something requires two types of transfers: [from Agent to Context] receiving the resource itself + Giving monetary value [to agent/peer]
Borrowing something requires at least three types of transfers: [Context] receiving the resource itself + Giving monetary value [to agent/peer] + returning the resource itself [from Context to agent/peer].
NOTE: I would not model Giving monetary value [to agent/peer] as a Purchase contribution.
Extend the model of this Exchange type. Material contributions can be in the form of
Giving something requires two types of transfers: [from Agent to Context] receiving the resource itself + Giving monetary value [to agent/peer] Borrowing something requires at least three types of transfers: [Context] receiving the resource itself + Giving monetary value [to agent/peer] + returning the resource itself [from Context to agent/peer].
NOTE: I would not model Giving monetary value [to agent/peer] as a Purchase contribution.