This calls for the date serial number to be stored, "as accurately as possible". This requirement is not precise and is untestable. Further, "as accurately as possible" may entail the use of codes such as arbitrary precision arithmetic, etc. which would have large performance penalties.
Proposed change: State the minimum precision required.
13.17.6.7 [p2529, 29]
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Proposed Disposition of DIS 29500 Comment GB-0369 (Modified: 2007-11-28) We agree; The following change will be made to Part 4, §3.17.6.7, page 2,529, line 29: As a date and/or time is represented by a number, a date/time serial value shall be stored in XML as the unformatted text form of that number (according to the lexical representation of numeric values given in § 3.17.5.3) , as accurately as possible . Similar Comments: CL-0148 , CO-0158 , DK-0034 , FR-0439 , GB-0366 , GR-0099 , IN-0071 , US-0169

In the proposed disposition, “as accurately as possible.” is still present.