IEEE Std 1394—1995, Standard for a High Performance Serial Bus, has been ratified and published by the IEEE. Recent discussions, commencing with a presentation at the Architecture working group meeting of the 1394 Trade Association in Bothell, Washington in July, 1995, have demonstrated a need for more detailed definitions of response code usage in clause 6, "Link layer specification", and clause 7, "Transaction layer specification", with respect to the uniform use of response codes. Action is underway to commence IEEE work on extensions and clarifications to IEEE Std 1394—1995; this work is expected to include revisions to the transaction layer specification. However, the proposed work is anticipated to take between twelve and eighteen months, commencing in January 1996. In the interim, industry consensus is needed to maintain interoperability between Serial Bus devices manufactured by different vendors. This specification addresses the clarifications needed in clauses 6 and 7 of the Serial Bus standard. Members of the 1394 Trade Association shall implement the LINK and TRAN layers in their products in accordance with this specification. Although the 1394 Trade Association is not an accredited standards body, its membership consists of the leading developers of Serial Bus products. This membership, for the most part, is also very active in the IEEE standards development process and intends to propose this specification for inclusion in the IEEE extensions to Serial Bus.