Verilog-2001 lets you use variables to select a group of bits from a vector.
Instead of being bounded by two explicit values, the variable part select is defined by the starting point of its range and the width of the vector. The starting point of the part select can vary. The width of the part select remains constant.
The following table lists the variable part selects symbols.
| Symbol | Meaning |
|---|---|
| + (plus) | The part select increases from the starting point. |
| - (minus) | The part select decreases from the starting point |