Choosing the IFC schema

Choosing the IFC schema

Goal: save your schedule in the IFC schema of the building model you want to merge it with.

When you need this

By default, the app saves a project as IFC 4.3 ADD2. That is the name of IFC 4.3 in the files that IfcOpenShell and Bonsai create. If you want to merge the schedule with a building model into one 4D file, for example with the MergeProjects recipe of IfcOpenShell (ifcpatch), both files must have the same schema. If the building model is an IFC4 file, IfcOpenShell refuses to merge it with an IFC 4.3 schedule. Then choose the schema of the model here.

Steps

1. Open Project settings: Settings › Project › Project settings, or File › Project settings.
2. Under IFC schema when saving, choose the schema of your building model.
3. Click Apply. The project is now Unsaved.
4. Save with Save (Ctrl+S) or Save as.

The three choices:

• IFC 4.3 ADD2 (default) writes IFC4X3_ADD2 in the header of the file.
• IFC 4.3 writes IFC4X3. That is how older versions of the app wrote IFC 4.3.
• IFC4 writes IFC4, for a building model in IFC4.

Pitfalls and what the app does

Merge as the last step. Do not open the merged 4D file (building model plus schedule) in the app to save it again. The app keeps only the schedule: the walls and the other parts of the building model are lost, also if you keep the schema. Change the schedule in your own file and merge again afterwards.

The app asks first when an opened file has another schema. If you open, for example, an IFC4 file, or an IFC 4.3 file from an older version of the app, the app does not simply change the file type. The first time you use Save or Save as, it first asks whether you keep the schema of the file or go to IFC 4.3 ADD2. Keep IFC4 (or Keep IFC 4.3) is the button that Enter chooses. If you close the question with Esc or the cross, the app saves nothing.

The app asks only once per file. Your choice is stored in the file itself. If you open it again later, the app does not ask again. If you choose a schema yourself in Project settings and click Apply, the app does not ask either.

A schema that the app cannot write, such as IFC2X3, opens in the app. The first time you save, the question says so, and you choose one of the three schemas above.

Auto-save and crash recovery ask nothing. They write the schema of the file and keep the question for the first time you save yourself. For a schema that the app cannot write, AutoSave does not write to the file until you have answered the question.

A new project asks nothing. A new project, and a project from another format such as XER, MPP or CSV, starts at IFC 4.3 ADD2 (default).

The content of the file does not change. The three schemas know the scheduling data that the app writes in the same way. Only the FILE_SCHEMA line in the header differs. So you lose nothing when you choose another schema.

An IFC 4.3 model from IfcOpenShell or Bonsai usually has IFC4X3_ADD2 in the header, like the default of the app. IfcOpenShell does not merge a schedule with IFC4X3 into it. If in doubt, look at the FILE_SCHEMA line at the top of the model file.

Undo does not change the schema. The schema belongs to the file, like the place where it is stored. A choice in Project settings and the answer to the question when saving are therefore not a step in Undo. To go back, choose the other schema in Project settings. That way AutoSave never silently writes another schema after you undo an edit.

See also

• New project and Project settings: all fields of the form.
• Files and formats: why IFC is the app's own format.
• Opening and saving a file: save and save as.