Changes3to4 – Project Haystack




Haystack 3 defined a total of 230 tags. Of these, 180 remain unchanged. The others have been modified as follows.

These are renamed or turned into conjuncts:

These tags are not ported:


In Haystack 3, weather stations were modeled via the weather tag, and their points were modeled via the weatherPoint tag. In Haystack 4, we use the weather marker on the points as the pointSubject. And stations are modeled via the weatherStation tag. Likewise, the weatherRef tag is now renamed to weatherStationRef.

Weather points are mapped from Haystack 3 to Haystack 4 as follows:

Haystack 3            Haystack 4             Notes
-------------------   --------------------   ------------------------
weatherCond           weatherCond            same
air temp              air temp               same
wetBulb temp          air wetBulb            pair with air not temp
apparent temp         air feelsLike          renamed, pair with air not temp
dew temp              air dewPoint           pair with air not temp
humidity              air humidity           pair with air
barometric pressure   atmospheric pressure   renamed
sunrise               daytime                renamed
precipitation         precipitation          same
cloudage              cloudage               same
solar irradiance      solar irradiance       same
wind direction        wind direction         same
wind speed            wind speed             same
visibility            visibility             same

See weatherStation children section for full list of points.


Most tags related to lighting have not been included pending the work under WG 705


Haystack 3 included a prototype for modeling networks, devices, and connections between them. It was never implemented by any vendors and was not complete, so it has not been ported to Haystack 4. However, some of the core concepts are found in the phIct library including:


Symbol is added as a new scalar type in Haystack 4. In Zinc, it is represented as ^name and in JSON with the "y:" prefix. The format version was left as "3.0" to minimize ecosystem disruption since symbols are only used with defs and unlikely to occur in normal Haystack data.