  We introduce simple cost and risk proxy metrics that can be attached to
Treasury issuance strategy to complement analysis of the resulting portfolio
weighted-average maturity (WAM). These metrics are based on mapping issuance
fractions to their long-term, asymptotic portfolio implications for cost and
risk under mechanical debt-rolling dynamics. The resulting mapping enables one
to visualize tradeoffs involved in contemplated issuance reallocation, and
identify an efficient frontier and optimal tenor. Historical Treasury issuance
strategy is analyzed empirically using these cost and risk metrics to
illustrate how changes in issuance needs and strategy have translated into
structural shifts in the cost and risk stance of Treasury issuance.
