Re: [sdw] WebVMT: Review metadata extension mechanism (#1102)

**SDW IG Review Summary (5/12/18)**

Syncing sensor data is a key feature of WebVMT mentioned in [Planned Features](http://w3c.github.io/sdw/proposals/geotagging/webvmt/#datasync), but not yet in the Data Model and Syntax sections. It should include prescribed attributes, e.g. speed, for compatibility and freeform attributes, e.g. prop6rpm, for flexibility.

@6a6d74 suggested using the attribute name to discriminate between prescribed and freeform by using an initial prefix, e.g. '#' to denote freeform, and recommending that the file also includes a comment to describe details of the meaning of that attribute, e.g. 'NOTE #prop6rpm is the rotational speed of propeller 6 in revs per minute.'

@tidoust highlighted the need to avoid characters with special meaning, e.g. avoid use of '.' which denotes object structure in Javascript and could cause confusion, e.g. obj['.speed'].

Consideration should be given to which prescribed attributes to include, i.e. sufficiently broad in scope but not exhaustive. Care should be taken to describe them in a clear and unambiguous way, e.g. 'speed' is the speed relative to the ground in km/h. Design activity is required, which is beyond the scope of this review.

_Conclusion_
   * Leave this issue open for now and revisit after data sync design has been documented.

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Received on Thursday, 6 December 2018 18:05:13 UTC