The input and output logic levels, sometimes known as logic values, of nodes and groups are defined with the following characters:
| Character: |
Logic Level: |
0 |
Forcing Low (GND) |
1 |
Forcing High (VCC) |
X |
Don't Care |
Z |
High impedance (no input to pin), for example, used for the "output" part of a bidirectional pin when the "input" part of the pin is driving in |
0 to 9, A to F |
Used for groups and interpreted as binary, decimal, hexadecimal, or octal values according to the current radix. The MSB is first; the LSB is last. |
DC |
Don't Care, unavailable for groups or state machine waveforms |
U |
Uninitialized |
H |
Weak High, unavailable for groups or state machine waveforms |
L |
Weak Low, unavailable for groups or state machine waveforms |
W |
Weak Unknown, unavailable for groups or state machine waveforms |
