The "protorel" property recently added to the output of action=query&meta=siteinfo&siprop=interwikimap was coded to include the property with a boolean true value rather than the API-standard empty string. This is now corrected, and will be deployed to WMF wikis with 1.24wmf10.

At some point in the future (timeframe and details undecided yet), I would like to change the API so that boolean properties like this one will actually be a truthy value (e.g. boolean true) in JSON and other output formats. It's likely that the backwards-compatible mode would cause any other properties that are currently returning as boolean true to change to empty-string.

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Brad Jorsch (Anomie)
Software Engineer
Wikimedia Foundation