On Saying "Imputation"

A friend has written to share a helpful quotation from Calvin.  In the 1536 edition of his Institutes, Calvin defends the use of the word "Trinity" and other "extra-biblical" words such as ousia and hypostasis as legitimate terms of art in systematic theology. At the end of his defense, he mentions that many common examples of useful and true theological terms could be mentioned. Then (in the 1536 edition but not in the 1559 edition) he uses "imputation" as a futher example:

"But what prevents us from explaining in clearer words those matters in Scripture which perplex and hinder our understanding, yet which faithfully serve the truth of Scripture itself, and are made use of sparingly and modestly and not at the wrong occasion? Daily examples occur. Men often debate on faith-righteousness, but few comprehend how we are made righteous by faith. Let us add that this is Christ's righteousness, not ours; it is lodged in him, not in us; but it becomes ours by imputation, since it is said to have been received by us. Thus the fact that we are not truly righteous, but imputatively so; or we are not righteous, but are reckoned righteous by imputation, inasmuch as we possess Christ's righteousness through faith, will be a matter plain and uncomplicated."

(Institution of the Christian Religion, 1536 edition. Battles translation, John Knox Press, 1975, p.62)