Examples of measurement type objects does not follow the standard (table C.15)

[petergarnaes]

As far as I can see in both the released standard and the draft, table C.15 says the field is called duration, but all examples instead names the field period.

The issue applies to:

• Listing C.6
• Section D.4
• Section D.5

[PaulVanSchayck]

We have, for now, used period in the implementation of the measurementType object in edr-pydantic. See this PR: KNMI/edr-pydantic#11

Also note that in some of the other examples (D.5) an invalid value (according to the spec) of "-PT10M/PT0M" is used. The use of this range to PT0M ("now"?) seems (to us) to be unnecessary as the spec already covers this by writing "A negative sign before a duration value (i.e. -PT10M) infers that the time start starts at the specified duration before the time value assigned to the parameter value."