6.55 RM D.8(47-49): Monotonic Time

"When appropriate, implementations should provide configuration mechanisms to change the value of Tick."

Such configuration mechanisms are not appropriate to this implementation and are thus not supported.

"It is recommended that Calendar.Clock and Real_Time.Clock be implemented as transformations of the same time base."

Followed.

"It is recommended that the best time base which exists in the underlying system be available to the application through Clock. Best may mean highest accuracy or largest range."

Followed.