FOREWORD Addendum 135.1d to ANSI/ASHRAE Standard 135-2009 contains a number of 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. 135.1-2009d-1. Add test to verify that COV subscription lifetimes are not affected by time-sync requests@ p.2. 135.1-2009d-2. Add new Active_COV_Subscription tests@ p. 4. In the following document@ language added to existing clauses of ANSI/ASHRAE 135.1-2009 and addenda is indicated through the use of italics@ while deletions are indicated by strikethrough. Where entirely new subclauses are added@ plain type is used throughout.