Scope and Assumptions This document provides metrics for linear television services as defined in ATIS-0800018@ IPTV Linear TV Service. These metrics generally facilitate performance measurement or monitoring@ unlike the fault codes in ATIS-0800028@ Fault Codes for IPTV@ which generally indicate hard faults. QoS metrics for public services are defined in ATIS-0800011 [11]. MPEG stream-layer QoS metrics are defined in ATIS- 0800040 [9]. This standard provides some guidance for metric application@ with more details provided in ATIS-0800041@ Implementer's Guide to QoS Metrics. Metrics for IPTV MPEG Transport Stream Monitoring are defined in ATIS-0800040 [9]. Multi-Program Transport Streams (MPTS) are not considered in this document. Referring to Figure 1@ the metrics defined in this document are focused toward the interface between the Network Provider and the Consumer; however they also apply to the interface between the Service Provider and Network Provider@ and the interface between the Content Provider and Service Provider. It is assumed that the ITF at startup ?C before the service is available ?C will be involved in a variety of setup/control communications with any IPTV oriented network/service attachment functions in the Service Provider (SP)/Network Provider (NP) networks. At this time@ the ATIS IIF does not analyze the traffic in the control plane associated with this action to determine the need for QoS metrics; this is for further study. This document generally assumes that MPEG Transport Stream (MPEG2-TS) on Real Time Protocol (RTP) encapsulation is used. The ATIS IIF does not assume that only RTP is used@ and allows MPEG2-TS directly over User Datagram Protocol (UDP) configurations [7]. It is understood that when RTP is not used@ this complicates accurate calculation of several metrics including dropped packets. Additional information/alternatives to calculate such metrics without RTP is for further study. This document also does not directly address the network architecture that maps video content directly to RTP packets not utilizing MPEG2-TS packets. This work is for further study. This standard defines an initial set of IPTV related audio metrics. Additional metrics may be of interest in the future@ such as Loudness Variation@ Overs/Unders@ Clipping@ etc.@ and these are for further study. Purpose The purpose of this document is to provide the industry with a set of well-defined QoS metrics for Linear (Broadcast) IPTV service.