Hello, Jim! I summarize below our remarks and questions regarding the ASN.1: 1. The fields "RandomVal" and "ranInt" are defined as unconstrained INTEGERs. Is there a specific reason for that? It is more accurate to define a range for them: for example (0..4294967295) . 2. In the definition below, what is the meaning for SEQUENCE containing NULL field? May be it is just a mistake: SEQUENCE instead of CHOICE? -- signing algorithm used must select one of these types of parameters -- needed by receiving end of signature. Params ::= SEQUENCE { null NULL, -- no value needed ranInt INTEGER OPTIONAL, -- some integer value iv8 IV8 OPTIONAL, -- 8 octet initialization vector ... } 3. The NonStandardParameter is locally redefined. Its meaning is a subset of the structure of the same name from H.225.0. Could we use the H.225.0 definition, instead of redefining it once again? 4. ALGORITHM-IDENTIFIER is defined and never used. 5. What is the reason for using the definitions of type "TYPE-IDENTIFIER.&Type" for single type only. For example: EncodedGeneralToken ::= TYPE-IDENTIFIER.&Type (ClearToken) -- general usage token Means EncodedGeneralToken ::= ClearToken -- general usage token 6. According to X.680, in the definitions of type "(WITH COMPONENTS {...," , it should be stated for each field what constrain is applied to it: PresenceConstraint ::= PRESENT | ABSENT | OPTIONAL | empty "empty" is syntactically right, but doesn't add any meaning in our case. For example: The following statement PwdCertToken ::= ClearToken (WITH COMPONENTS {..., timeStamp, generalID }) doesn't provide any additional information to already defined: ClearToken ::= SEQUENCE -- a `token' may contain multiple value types. { timeStamp TimeStamp OPTIONAL, password Password OPTIONAL, dhkey DHset OPTIONAL, challenge ChallengeString OPTIONAL, random RandomVal OPTIONAL, certificate TypedCertificate OPTIONAL, generalID Identifier OPTIONAL, nonStandard NonStandardParameter OPTIONAL, ... } Shouldn't it have been explicitly stated as PRESENT? 7. The two above remarks (5 and 6) apply to H.225.0 as well. Look for: FastStartToken ::= ClearToken (WITH COMPONENTS {..., timeStamp, dhkey, generalID -- set to 'alias' -- }) EncodedFastStartToken ::= TYPE-IDENTIFIER.&Type (FastStartToken) Thank you, Orit Levin RADVision Inc. E Mail: orit@radvision.com 575 Corporate Dr., Suite 420 Tel: 201-529-4300 ext. 230 Mahwah, NJ 07430 Fax: 201-529-3516