IEEE Std 181-2011 pdf download – IEEE Standard for Transitions, Pulses, and Related Waveforms.
transient: Any contiguous region of a waveform that begins at one state, leaves and subsequently returns to that state, and contains no state occurrences. transition: Contiguous region of a waveform that connects, either directly or via intervening transients, two state occurrences that are consecutive in time but are occurrences of different states. transition, negative-going: A transition whose terminating state is more negative than its originating state. NOTE 1- The endpoints of the negative going transition are the last exit of the waveform from the higher state boundary and the first entry of the waveform into the lower state boundary. NOTE2- The term falling edge is deprecated because 1) the word edge describes the property of a geometric figure, which is not contained by, or representative of, the physical signal that corresponds to the waveform, and 2) the word falling refers to motion or position of physical objects. transition, pass through: The transition from an initial state to a nonconsecutive state through any number of other states where the cduration in these other states is less than the duration for state occurrence. transition, positive-going: A transition whose terminating state is more positive than its originating state. NOTE 1- The endpoints of the positive-going transition are the last exit of the waveform from the lower state boundary and the first entry of the waveform into the higher state boundary. NOTE 2- The term rising edge is deprecated because 1) the word edge describes the property of a geometric figure, which is not contained by, or representative of, the physical signal that corresponds to the waveform, and 2) the term rising refers to motion or position of physical objects. transition duration: The difference between the two reference level instants of the same transition. Unless otherwise specified, the two reference levels are the 10% and 90% reference levels.