I think 'indirect' in property names should be 'indirection', so I will assume that in what follows. I am not happy with 'indirectionEmptyValue' or 'indirectionMissingValue'. Both 'empty' and 'missing' are concepts with well-defined meanings in DFDL. How about 'indirectionInactiveValue' or better 'indirectionUnusedValue'? My stab at an updated grammar below (changes in blue). There is no concept of an empty indirection value or a nil indirection value, so we don't need those clauses. I also think we can simplify the EnclosedElement construct (changes in red ) Bradd I know you were struggling with how to link the target of the indirection into the main grammar, as it is dis-contiguous. I think we can achieve that by incorporating the target(s) into the Document as a whole. If we think that the concept of an indirection can only ever happen inside a complex type, then we could move IndirectionRep from SimpleElement/ComplexElement to EnclosedElement. I don't think it is worth getting more specific with IndirectElement. Specifically, it has no LeadingAlignment or TrailingAlignment, but to reflect that requires duplicating most of the rest of the grammar. You have not disallowed lengthKind 'prefixed' for the 'indirectionType', so that is included in the grammar. Productions Document = DocumentElement IndirectElement* DocumentElement = SimpleElement | ComplexElement SimpleElement = SimpleLiteralNilElementRep | SimpleEmptyElementRep | SimpleNormalRep | IndirectionRep SimpleEnclosedElement = SimpleElement | AbsentElementRep ComplexElement = ComplexLiteralNilElementRep | ComplexNormalRep | ComplexEmptyElementRep | IndirectionRep ComplexEnclosedElement = ComplexElement | AbsentElementRep EnclosedElement = SimpleElement | ComplexElement | AbsentElementRep IndirectElement = SimpleElement | ComplexElement AbsentElementRep = Absent IndirectionRep = IndirectionLeftFraming PrefixLength IndirectionContent IndirectionRightFraming IndirectionLeftFraming = LeadingAlignment IndirectionRightFraming = TrailingAlignment IndirectionContent = LeftPadding [ IndirectionValue | IndirectionUnusedValue ] RightPadOrFill IndirectionValue = SimpleValue SimpleEmptyElementRep = EmptyElementLeftFraming EmptyElementRightFraming ComplexEmptyElementRep = EmptyElementLeftFraming EmptyElementRightFraming EmptyElementLeftFraming = LeadingAlignment EmptyElementInitiator PrefixLength EmptyElementRightFraming = EmptyElementTerminator TrailingAlignment SimpleLiteralNilElementRep = NilElementLeftFraming [NilLiteralCharacters | NilElementLiteralContent] NilElementRightFraming ComplexLiteralNilElementRep = NilElementLeftFraming NilLiteralValue NilElementRightFraming NilElementLeftFraming = LeadingAlignment NilElementInitiator PrefixLength NilElementRightFraming = NilElementTerminator TrailingAlignment NilElementLiteralContent = LeftPadding NilLiteralValue RightPadOrFill SimpleNormalRep = LeftFraming PrefixLength SimpleContent RightFraming ComplexNormalRep = LeftFraming PrefixLength ComplexContent ElementUnused RightFraming LeftFraming = LeadingAlignment Initiator RightFraming = Terminator TrailingAlignment PrefixLength = SimpleContent | PrefixPrefixLength SimpleContent PrefixPrefixLength = SimpleContent SimpleContent = LeftPadding [ NilLogicalValue | SimpleValue ] RightPadOrFill ComplexContent = Sequence | Choice Sequence = LeftFraming SequenceContent RightFraming SequenceContent = [ PrefixSeparator EnclosedContent [ Separator EnclosedContent ]* PostfixSeparator ] Choice = LeftFraming ChoiceContent RightFraming ChoiceContent = [ EnclosedContent ] ChoiceUnused EnclosedContent = [ EnclosedElement | Array | Sequence | Choice ] Array = [ EnclosedElement [ Separator EnclosedElement ]* [ Separator StopValue] ] StopValue = SimpleElement LeadingAlignment = LeadingSkip AlignmentFill TrailingAlignment = TrailingSkip RightPadOrFill = RightPadding | RightFill | RightPadding RightFill Regards Steve Hanson IBM Hybrid Integration, Hursley, UK Architect, IBM DFDL Co-Chair, OGF DFDL Working Group smh@uk.ibm.com tel:+44-1962-815848 mob:+44-7717-378890 Note: I work Tuesday to Friday From: Bradd Kadlecik/Poughkeepsie/IBM To: Steve Hanson/UK/IBM Cc: DFDL-WG <dfdl-wg@ogf.org>, "dfdl-wg" <dfdl-wg-bounces@ogf.org>, Mike Beckerle <mbeckerle.dfdl@gmail.com> Date: 09/07/2020 15:09 Subject: Re: [EXTERNAL] Re: [DFDL-WG] DFDL pointer & offset proposal I have updated the document proposal with proposed DFDL grammar changes: Regards, Bradd Kadlecik z/TPF Development Phone: 1-845-433-1573 E-mail: braddk@us.ibm.com 2455 South Rd Poughkeepsie, NY 12601-5400 United States Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU