Remarks_questions_OData_version_4_CBS_beta.txt

Remarks questions OData version 4 CBS beta.

- is there a place where I can post questions of this kind without troubling all followers of the LinkedIn group 
   `Centraal Bureau voor de Statistiek; Open Data` ?
   
- is there documentation about OData version 4 apart from the terrible https://lnkd.in/dkQMqWR and friends?

- Nesting of commands is not allowed?

    The functions (?) `indexof` and `tolower` work standalone but using the filter 
    `$filter=indexof(tolower(Title),'gas') eq 9` returns an incomplete json statement:

    {"@odata.context":"https://beta.opendata.cbs.nl/OData4/CBS-Maatwerk/900001NED/$metadata#MeasureCodes","value":[

    In browser (Firefox 62.0.3)
    https://beta.opendata.cbs.nl/OData4/CBS-Maatwerk/900001NED/MeasureCodes?$filter=indexof(tolower(Title),%27gas%27)%20eq%209
    SyntaxError: JSON.parse: unexpected end of data at line 1 column 112 of the JSON data

- Is there a reason that the filter 
      $filter=(Id lt 6 and Id gt 3) or (Id eq 8) or (Id le 15 and Id ge 12)
    on Observations returns the rows in the order 12,13,14,15,4,5,8 ?
    It looks like they are sorted as characters. But I don't ask them to be sorted!
    And if I ask them to be sorted
      $filter=(Id lt 6 and Id gt 3) or (Id eq 8) or (Id le 15 and Id ge 12)&$orderby=Id asc
    then they are sorted numerically 4,5,8,12,13,14,15 (as I would expect)

- implementation document https://beta.opendata.cbs.nl/OData4/implement.html
    * under heading Metadata the old catalog (CBS) is used instead of CBS-Maatwerk
    * the $filter(toupper) example has a copy-paste error
    * $orderby seems to work (but is not mentioned)