# \[SOLVED\] How to classify steel fixing plates?

**URL:** <https://forums.buildingsmart.org/t/solved-how-to-classify-steel-fixing-plates/1989>\
**Category:** Users\
**Created:** [November 9, 2019, 11:47pm UTC](https://forums.buildingsmart.org/t/solved-how-to-classify-steel-fixing-plates/1989 "2019-11-09T23:47:24Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Moult](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/moult/32/196_2.png) [@Moult](https://forums.buildingsmart.org/u/Moult)\
**Post date:** [November 9, 2019, 11:47pm UTC](https://forums.buildingsmart.org/t/solved-how-to-classify-steel-fixing-plates/1989/1 "2019-11-09T23:47:24Z")

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As shown in the below image - what IFC class do the gold elements belong to? The bolts belong to `IfcMechanicalFastener` with `PredefinedType = BOLT`, but what about the metal plates and stiffeners?

I would imagine it is `IfcPlate`, as shown [here](https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/ifcplate.htm) but there are some conflicting descriptions. The first is that the page says:

> NOTE Definition according to ISO 6707-1: thin, rigid, flat, metal product, of a thickness greater than that of a sheet.

So this seems correct, it is a thin, rigid, flat, metal product, with a thickness greater than a sheet. However. the [`IfcPlateTypeEnum`](https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/ifcplatetypeenum.htm) only gives 4 enums: it is obviously not a `CURTAIN_PANEL` and the name `SHEET` implies a thin sheet, kind of like what I’d usually expect for a `IfcCovering` with `PredefinedType=CLADDING` for thin metal cladding sheets. This leaves me with `USERDEFINED`, which I’d rather avoid since this is a very common element and `NOTDEFINED` which again I’d rather avoid if there is a better choice.

Perhaps it falls under `IfcDiscreteAccessory`, as it is an “accessory”, perhaps, although it only has `IfcDiscreteAccessoryTypeEnum` for `ANCHORPLATE`, `BRACKET`, and `SHOE`, of which this is none of them.

Ideas?

 ![2019-11-10-103303_832x473_scrot](https://us1.discourse-cdn.com/flex016/uploads/buildingsmart1/original/1X/0524e382ab235fb22f08ea0a8132eecb1c2cc571.png)

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**Author:** ![Moult](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/moult/32/196_2.png) [@Moult](https://forums.buildingsmart.org/u/Moult)\
**Post date:** [November 10, 2019, 3:25am UTC](https://forums.buildingsmart.org/t/solved-how-to-classify-steel-fixing-plates/1989/2 "2019-11-10T03:25:55Z")

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Marking as solved - Ehsan sent me a message saying that this had been fixed in the latest IFC4 version. It should be `IfcPlate` - the latest version (after the latest ISO one) has new plate enums for this object. All good!

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**Author:** ![TLiebich](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/tliebich/32/71_2.png) [@TLiebich](https://forums.buildingsmart.org/u/TLiebich)\
**Post date:** [November 11, 2019, 7:12am UTC](https://forums.buildingsmart.org/t/solved-how-to-classify-steel-fixing-plates/1989/3 "2019-11-11T07:12:46Z")

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Ehsan is right.  
These extensions have been made for IFC4.2 (corresponding with IFC Bridge). When exporting IFC4, best to use IfcPlate.PredefinedType = .USERDEFINED. and ObjectType =“Flange Plate” (or similar).