Hi,
I have a question on how to define on a class and specially with the PropertyType parameter that can accept two values : Property and Dependancy.
I will take the exemple of the red door class. This class is define by
IfcClass=IfcDoor
Color=Red
This class can have multiple property assigned like height and FireResistance.
In that exemple, the color=red will be considered a dependency. And that property define the class.
The other property are describing the class without defined them. (A red door can exist with or without FireResistance).
Is it the right way to understand PropertyType ?
Or should i use IsWritable ?
For me, a BSDD class is defined by properties. At the same time, it define other properties.
I think that PropetyType is the metadata i am looking for but the documentation is not defining “Dependency”. I found the doc here: ://technical.buildingsmart.org/services/bsdd/data-structure/
PropertyType
Text
Type of the Property for the Class: Property (default) or Dependency
Hi @Jocelin, I’m the bSDD manager, and I will try to help.
“PropertyType": “Dependency” is something that was implemented to reflect the functionality of the ISO standard, but because it was never used in practice, we are considering removing that feature in the near future. I recommend not using this attribute. According to the standard ISO12006-3: “Dependency means that the current property’s value may change if the value of one of the related properties is changed.“ Similar goal can be achieved with “ConnectedPropertyCodes” that is reflecting another standard - ISO23386.
You mentioned “IsWritable” - that is rarely used as well, and I don’t know any software making use of it in practice.
If you want to define a class “Red door”, easiest would be to define a class called like that. You can make those multi-property dependencies in form of specification using the IDS standard.
I don’t want to use IDS either to describe this relationship between an object and his property.
I want to do it the other way around, manage property with BSDD and create on the go an IDS.
In reality, I think I am looking for is a translation from BSDD to IDS.
IDS has two principle to create a relationship between a class and a property
Applicability: which has no translation in BSDD
Requirements: which has a translation in BSDD
I went again threw ISO12006-3, and my understanding is may be better.
ISO Concept
I would use the XtdFilter on the XtdSubject, in order to specify property that define my subject.
That part of ISO would fit my purpose.
In my previous example:
Color : is a filtering property of the class with the value « Red »
FireResistance : is a property of the class