FOREWORD This addendum describes changes to the current standard. These modifications are the result of change proposals made pursuant to the ASHRAE continuous maintenance procedures and of deliberations within Standing Standard Project Committee 135. The changes are summarized below. 135-2008q-1. Allow unicast I-Ams@ p. 1. 135-2008q-2. Define virtual addressing for data links with MAC addresses longer than 6 octets@ p. 2. 135-2008q-3. Define the use of ZigBee as a BACnet data link layer@ p. 3. In the following document@ language to be added to existing clauses of ANSI/ASHRAE 135-2008 and Addenda is indicated through the use of italics@ while deletions are indicated by strikethrough. Where entirely new subclauses are to be added@ plain type is used throughout. SSPC 135 wishes to recognize the efforts of the following people in developing this addendum: Coleman Brumley@ Ted Humpal@ Ren?? K?lin@ Jerry Martocci@ Bob Old@ Bob Thomas@ and Cam Williams.