IEEE 1801-2018, Unified Power Format , is a Standard for design and verification of low-power, energy-aware electronic systems. The standard specifies the commands that make up a Tcl script that describes the power intent of a system on chip.
The power intent for each system is stored in a separate. When subsystems are combined, the various power intents can be read, forming a single dataset that can then be used to verify the combined power intent. A simulator is usually used to perform the verification. Since a power intent is evaluated as a Tcl script in order to populate the combined dataset, Unified Power Language would have been a more apt name.