Attributes may be used to retrieve information about an object or an expression. For expression X:
|X'size||returns the number of bits in X|
|X'msb||returns the value of the most significant bit of X|
|X'meta||returns 1 if X contains metadata, and 0 otherwise|
|X'offset||returns the offset of X, in bits, when X is an array element or structure member. If X evaluates to a stream, it instead returns the current location in that stream|
|X'last||returns a previous value of the operand|
These attributes are actually postfix operators, and their use is therefore not restricted to objects. They may be used anywhere where a postfix operator is allowable.