The figure in the SBML spec describes what is required and what is optional in the 'History' element (section 6.6) but the text under the figure does not completely recapitulate this information (explicitly listing what is optional and what is required). It should do so, to be more clear.
I am accepting this issue as valid.
I am accepting this issue as valid.
I agree with the proposed change and that it should be done.
I am accepting this issue as valid.
I am accepting this issue as valid.
Moving his to status 'Pending' and adding it to the list of known errata at http://sbml.org/Documents/Specifications/SBML_Level_3/Version_1/Core/Confirmed_issues_in_the_Level_3_Version_1_Core_Specification
This change is now in SVN, and will be incorporated into the upcoming releases of the L2v5 and L3v2 specifications. Also, added L2v4 as a label to the issue, as it had the exact same problem.