**Formal Definition**

Vectors are multiple bit widths **net** or **reg** data type variables that can be declared by specifying their range.

**Simplified Syntax**

net_type** ****[msb:lsb]** list_of_net_identifiers;

**reg** **[msb:lsb]** list_of_register_identifiers;

**Description**

Vector range specification contains two constant expressions: the msb (most significant bit) constant expression, which is the left-hand value of the range and the lsb (least significant bit) constant expression, which is the right-hand value of the range. The msb and lsb constant expressions should be separated by a colon.

Both the msb constant expression and the lsb constant expression can be any value - positive, negative, or zero. The lsb constant expression can be greater, equal or less than the msb constant expression.

Vectors can be declared for all types of **net** data types and for **reg** data types. Specifying vectors for **integer**, **real**, **realtime**, and **time** data types is illegal.

Vector nets and registers are treated as unsigned values (see: Arithmetic expressions with registers and integers for more explanations).

**Examples**

Example 1

**reg** [3:0] addr;

The 'addr' variable is a 4-bit vector register made up of addr[3] (the most significant bit), addr[2], addr[1], and addr[0] (the least significant bit).

Example 2

**wire** [-3:4] d;

The d variable is 8-bit vector net made up of d[-3] (msb), d[-2], d[-1], d[0], d[1], d[2], d[3], d[4] (lsb).

Example 3

**tri** [5:0] x, y, z;

The above line declares three 6-bit vectors.

**Important Notes**

- Both the msb and the lsb expressions should be constant expressions.
- The msb and the lsb constant expressions may be positive, negative, or zero.
- The lsb constant expression may be greater, equal or less than the msb constant expression.
- Vectors can be declared only for
**nets**and**reg**data types. - Vector declaration for
**integer**,**real**,**realtime,**and**time**data types are illegal.

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