Fixed Point Subtypes inheriting Small 87-02-10 AI-00521/00 1 !standard 03.05.09 (14) 87-02-10 AI-00521/00 !class study 87-02-10 (provisional classification) !status received 87-02-10 !topic Fixed Point Subtypes inheriting Small !summary 87-02-10 !question 87-02-10 !recommendation 87-02-10 !wording 87-02-10 !discussion 87-02-10 !appendix 87-02-10 ***************************************************************************** !section 03.05.09 (14) Terry Froggatt 86-12-05 83-00884 !version 1983 !topic Fixed Point Subtypes inheriting Small 3.5.9 (14) states, and 3.5.9 (16) clarifies, that a fixed point subtype S of a fixed point type T, inherits the Small of T if and only if that Small was specified by a length clause. However, I imagine that most fixed point types will have a small length clause to ensure that Small is Delta rather than a power of 2. I cannot see small length clauses being used to produce a much smaller small than the delta, since this this can be achieved by using a smaller delta. A subtype of T which inherits T's small can always be obtained by using a range constraint rather than a fixed-point constraint; so if a fixed-point constraint is given it should be honoured. Thus, the Small of S should be the largest power of 2 times the Small of T that is not more than the Delta of the fixed-point constraint; regardless of whether T's Small was specified or defaulted.