Time-stamps are labels which a system adds to its data items. These la
bels enable the system to keep track of the temporal precedence relati
ons among its data elements. Many distributed protocols and some appli
cations use the natural numbers as time-stamps. The natural numbers ho
wever are not useful for bounded protocols. In this paper we develop a
theory of bounded time-stamps. Time-stamp schemes are defined and the
complexity of their implementation is analyzed. This indicates a dire
ction for developing a general tool for converting time-stamp based pr
otocols to bounded protocols.