I recently discovered some useful fields for CPQ in connection with the Asset record. They are there to assist in connecting back to the original Quote Line. They also provide extra details in the scenario that your Asset is connected to a percent of total Subscription Product.

Quote Line: This reflects the Quote Line that created the Asset Record it is connected to.

Latest Quote Line: If this Quote Line is impacted by an Amendment, this will show the most recent Quote Line related to this Asset.

Subscription Quote Line: This field gives the Quote Line of the Subscription Quote Line, if there is a related percent of total product.

There is also a related list on Asset called Quote Lines, which shows the related Quote Lines when the Asset is connected to a renewal Quote Line through a Subscription product.