Describe the types of attributes?

Types of attributes: An attribute's category determines the type of values that are permitted in the attribute. For instance, the value version 1 is not valid for an attribute described as an integer, but the value 1 is valid. Numeric types (such as integer or real) can also be limited to a predefined range through their attribute definition.

Choice : An attribute along with a list of predefined values.

ID Reference: An attribute along with a value which is a Unique ID value from another element. It is typically used for element-based cross-references.

ID References: An attribute along with a value of one or more Unique ID values from another part.

Integer: An attribute along with a whole number value (no decimal parts). Examples of valid integers are 22, -22, and +322. An integer could be described to fall within a range.

Integers: An attribute along with a value of one or more integers. Enter each number on a separate line within the Attribute Value text box.
Real An attribute along with a real number value, with or without a decimal part (the value could also be expressed within scientific notation). Examples of valid real numbers are 2, 22.4, -1 0.22, and 2.3e. A real number could be described to fall inside a range.