Correct Appendix A for flag_values attribute

[jonathan]

This is a proposed correction for an error in the documents, not a change to the standard. According to the rules, it will be accepted if no-one objects to it in the next three weeks.

The table in Appendix A incorrectly states that flag_values is a string attribute. This is inconsistent with CF 3.5, which says, "The flag_values attribute is the same type as the variable to which it is attached." This error was pointed out by John Stark in April 2007 ​http://www.cgd.ucar.edu/pipermail/cf-metadata/2007/001614.html and this month by Philippe Poilbarbe on the netCDF email list.

The correction required is as follows:

• Add "D for the type of the data variable" to the sentence "The Type values are S for string, N for numeric" before the table in Appendix A.

• Change the type from S to D for flag_values in the table.

• In the conformance document, add a section:

  3.5 Flags
  Requirements:
  The flag_values attribute must have the same type as the variable to which it is attached.
  

Jonathan

[mlaker1]

Corrected the flag_values attribute.