The IBA specification defines many different types of attributes:
An attribute may be very simple and consists of a single item. An example would be the LEDInfo (Light-Emitting Diode Information) attribute.
An attribute may take the form of a table. An example would be the LinearForwardingTable attribute in a switch.
An attribute may consists of data structure containing a number of elements. An example would be the PortInfo attribute.
As just discussed, many attributes are actually comprised of a series of elements (the specification frequently refers to them as components). As an example, the PortInfo attribute is a data structure containing 46 elements (see Table 29-5 on page 825). The specification references a particular element of a multi-element attribute using the following format:
AttributeName.ElementName
Some examples would be:
PortInfo.M_Key
PortInfo.LID
PortInfo.Capabilitymask
SMInfo.GUID
SMInfo.ActCount
SwitchInfo.LinearFDBCap
SwitchInfo.DefaultPort
In this book, the author has italicized all instances of attributes and their elements.