x_relations to communicate courser resolutions of data

[jbfaden]

Eelco Doorbos has implemented a way to get courser, and more quickly loading, versions of a dataset. This is done with x_relations, and describes another dataset with a time tag. For example:

https://data.spaceweather.knmi.nl/hapi/info?dataset=brik_ii_electron_density has:

"x_relations": [
   {
       "id": "brik_ii_electron_density_PT0_250S",
       "description": "Electron density data from the BRIK-II scintillation monitor, downsampled to 5 millisecond cadence",
       "cadence": "PT0.250S",
       "type": "resample",
       "method": "max",
       "add": "automatic"
   }
]

indicating that a reduced set 0.250 second cadence is available. These are the maximum values within the interval.

His JavaScript viewer knows to look for courser versions of the data.