public const string IFCEngineDLL = @"IFCEngine.dll";

[DllImport(IFCEngineDLL, EntryPoint = "sdaiCreateAggr")]
public static extern Int64 sdaiCreateAggr(Int64 instance, Int64 attribute);    

Property instance

Size: 64 bit / 8 byte (value)
Handle of an instance within an IFC file, for example #31313 = IFCWALLSTANDARDCASE(...)

Property attribute

Size: 64 bit / 8 byte (value)
A handle to the an attribute of a certain entity, for example attribute Name of entity IFCROOT.


Here you can find code snippits that show how the API call sdaiCreateAggr can be used.

Int64 localCreateAggrBN(Int64 instance, byte[] attributeName)
    //  This function is an alternative to the API call sdaiCreateAggrBN()
    //  based on sdaiCreateAggr().
    //  Use of sdaiCreateAggr() can lead to performance improvement compared to sdaiCreateAggrBN().
    Int64 instanceType = IfcEngine.x64.sdaiGetInstanceType(instance),
          attribute = IfcEngine.x64.sdaiGetAttrDefinition(instanceType, attributeName);

    return IfcEngine.x64.sdaiCreateAggr(instance, attribute);