# Terms and Syntax

The following are special terms and syntax used in this chapter to describe functionality of the classes with respect to their associated operations.

## Ivec Class Syntax Conventions

The name of each class denotes the data type, signedness, bit size, and number of elements using the following generic format:

`<type><signedness><bits>vec<elements>`

`{ F | I } { s | u } { 128 | 64 | 32 | 16 | 8 } vec { 16 | 8 | 4 | 2 | 1 }`

where

`type` | Indicates floating point ( `F` ) or integer ( `I` ).
`signedness` | Indicates signed ( `s` ) or unsigned ( `u` ). For the Ivec class, leaving this field blank indicates an intermediate class. For the Fvec classes, this field is blank because there are no unsigned Fvec classes.
`bits` | Specifies the number of bits per element.
`elements` | Specifies the number of elements.

## Special Terms and Conventions

The following terms are used to define the functionality and characteristics of the classes and operations defined in this manual.

- Nearest Common Ancestor: This is the intermediate or parent class of two classes of the same size. For example, the nearest common ancestor of Iu8vec8 and Is8vec8 is I8vec8, and the nearest common ancestor between Iu8vec8 and I16vec4 is M64.

- Casting: Changes the data type from one class to another. When an operation uses different data types as operands, the return value of the operation must be assigned to a single data type, and one or more of the data types must be converted to a required data type. This conversion is known as a typecast. While typecasting is occasionally automatic, in cases where it is not automatic you must use special syntax to explicitly typecast it yourself.

- Operator Overloading: This is the ability to use various operators on the user-defined data type of a given class. In the case of the Ivec and Fvec classes, once you declare a variable, you can add, subtract, multiply, and perform a range of operations. Each family of classes accepts a specified range of operators, and must comply by rules and restrictions regarding typecasting and operator overloading as defined in the header files.

Parent topic: Integer Vector Classes