Like variables, each attribute has a data type that determines what kind of value it can hold. Attributes in Maya are usually floats or booleans, with vector, integer or string attributes being less common.
Vector array data types are useful for animating position, velocity, acceleration, color (using the three values to represent RGB), and other particle attributes made of three components.
Particle shape nodes have compound data types not seen in other built-in attributes:
These are also called per particle attributes.
Only particle objects have vector array and float array attributes. The default vector array attributes for particle objects are position, velocity, and acceleration. These are also called per particle attributes because you can set the attribute for each particle to different values.
Data types of custom attributes
When you add a custom attribute to an object with Modify > Add Attribute, you select whether its data type is floating point, integer, Boolean, or vector.