Rhino can read STEP files, but all the associated data is lost.
tutorial.step (19.9 KB)
Does rhino have any support to read such attributes from STEP?
It would super-duper-awesome if these strings would be kept rhino object user strings.
By data I mean simple key value pairs you can see in the image below on the right side:
Hi @Petras_Vestartas ,
I think this is why IFC is used (upcoming replies: āNot true, IFC is based on a schemaā¦ā) 
You can try to read the STEP file itself as a .txt file. Because it is basically a text file.
Then check for those tags (SDAI, productā¦) in the text, and extract its values.
I think this is the only way.
HI Petras -
Iāve added the feature request: RH-88499 File IO: STEP MetaData
-wim
Thank you, hopefully this will be available
Hi Petras,
Thank you for the stp file you gave Wim with metadata in it. I think itās what we need. However, even as simple as it is, it would be handy to have something simpler yet. Is there any chance you could make a stp file that has a single line, or point, with one userdata attached? Itās really tricky following through all of the connections in a step file (Iām doing it in a text editor) and Iām hoping this will help me figure it out.
Cheers,
Tim
Hi,
Thank you for helping with this issue.
I exported even a simpler model that contains no hierarchy. Just one simple cylinder with 3 attributes:
tutorial.zip (2.0 KB)
Hereās a similar topic from a few years ago:
The file in this post has metadata from Artec Studio
Yes this is the same issue, but McNeel have not implemented yet.
I added this feature for OpenCascade:
But now it has to be read in rhino.
Hi Petras,
Thank you for your effort, it is truly appreciated. But even the cylinder is a more than I need. It comes in as a brep so there are faces, surfaces, trim curves etc. Iād really like a point with one userdata on it. What Iām trying to achieve is to be able to see the geometry, userdata and the entities that connect them in a single screen.
Tim
I shouldnāt say ācomes in asā. I should āexists in the file asā. Way more than a screens worth just for the cylinder itself.
As simple as it gets, single point from OpenCascade.
A point must be part of a topological shape so I give you a smallest entity I can serialize to step the attribute is defined in line #35:
ISO-10303-21;
HEADER;
FILE_DESCRIPTION(('Open CASCADE Model'),'2;1');
FILE_NAME('Open CASCADE Shape Model','2025-07-24T16:03:05',('Author'),(
'Open CASCADE'),'Open CASCADE STEP processor 8.0','Open CASCADE 8.0'
,'Unknown');
FILE_SCHEMA(('AUTOMOTIVE_DESIGN { 1 0 10303 214 1 1 1 1 }'));
ENDSEC;
DATA;
#1 = APPLICATION_PROTOCOL_DEFINITION('international standard',
'automotive_design',2000,#2);
#2 = APPLICATION_CONTEXT(
'core data for automotive mechanical design processes');
#3 = SHAPE_DEFINITION_REPRESENTATION(#4,#10);
#4 = PRODUCT_DEFINITION_SHAPE('','',#5);
#5 = PRODUCT_DEFINITION('design','',#6,#9);
#6 = PRODUCT_DEFINITION_FORMATION('','',#7);
#7 = PRODUCT('MyPoint','MyPoint','',(#8));
#8 = PRODUCT_CONTEXT('',#2,'mechanical');
#9 = PRODUCT_DEFINITION_CONTEXT('part definition',#2,'design');
#10 = GEOMETRICALLY_BOUNDED_WIREFRAME_SHAPE_REPRESENTATION('',(#11,#15),
#17);
#11 = AXIS2_PLACEMENT_3D('',#12,#13,#14);
#12 = CARTESIAN_POINT('',(0.,0.,0.));
#13 = DIRECTION('',(0.,0.,1.));
#14 = DIRECTION('',(1.,0.,-0.));
#15 = GEOMETRIC_CURVE_SET('',(#16));
#16 = CARTESIAN_POINT('',(1.,2.,3.));
#17 = ( GEOMETRIC_REPRESENTATION_CONTEXT(3)
GLOBAL_UNCERTAINTY_ASSIGNED_CONTEXT((#21)) GLOBAL_UNIT_ASSIGNED_CONTEXT(
(#18,#19,#20)) REPRESENTATION_CONTEXT('Context #1',
'3D Context with UNIT and UNCERTAINTY') );
#18 = ( LENGTH_UNIT() NAMED_UNIT(*) SI_UNIT(.MILLI.,.METRE.) );
#19 = ( NAMED_UNIT(*) PLANE_ANGLE_UNIT() SI_UNIT($,.RADIAN.) );
#20 = ( NAMED_UNIT(*) SI_UNIT($,.STERADIAN.) SOLID_ANGLE_UNIT() );
#21 = UNCERTAINTY_MEASURE_WITH_UNIT(LENGTH_MEASURE(1.E-07),#18,
'distance_accuracy_value','confusion accuracy');
#22 = PRODUCT_RELATED_PRODUCT_CATEGORY('part',$,(#7));
#23 = MECHANICAL_DESIGN_GEOMETRIC_PRESENTATION_REPRESENTATION('',(#24),
#17);
#24 = STYLED_ITEM('color',(#25),#15);
#25 = PRESENTATION_STYLE_ASSIGNMENT((#26));
#26 = SURFACE_STYLE_USAGE(.BOTH.,#27);
#27 = SURFACE_SIDE_STYLE('',(#28));
#28 = SURFACE_STYLE_FILL_AREA(#29);
#29 = FILL_AREA_STYLE('',(#30));
#30 = FILL_AREA_STYLE_COLOUR('',#31);
#31 = DRAUGHTING_PRE_DEFINED_COLOUR('green');
#32 = PROPERTY_DEFINITION('my_attribute_for_Tim',$,#5);
#33 = PROPERTY_DEFINITION_REPRESENTATION(#32,#34);
#34 = REPRESENTATION('my_attribute_for_Tim',(#35),#17);
#35 = DESCRIPTIVE_REPRESENTATION_ITEM('my_attribute_for_Tim',
'as_small_as_it_gets');
ENDSEC;
END-ISO-10303-21;
That is fanfrickentastic. Exactly what I wanted. Thank you.
Just a heads up. Even with the super simple step file Iām having a hard time figuring out how to get at the DESCRIPTIVE_REPRESENTATION_ITEM in code. I no longer have access to sample code either. All I have to work with is the plugins we currently have and StepToolsā header files.
I would not expect anything soon. Sorry I donāt have better news.
Tim
Hi Tim,
any news on this side?
Iāve a client that need to export multiple attributes to another platform and Step seems the way to do this.
Hi skysurfer,
Sorry, I couldnāt figure it out. So, no new news.
Tim
I did a pull request to OpenCanscade, which is now merged. Now you can now write and read step with attributes. For sure it is not rhino but technically you could write a converter from Rhino Brep to OpenCascade Brep.
I am wondering even if rhino step format was implemented from scratch or started from existing code somewhere as it is a big thing to write.
You mean that using OpenCascade I can add the metadata to a STEP file?
Also if this not happen directly in Rhino it could be a temporary solution.
Yes it can, I added that option and it is already merged: 0033896 - STEP Write - General Attributes by petrasvestartas Ā· Pull Request #634 Ā· Open-Cascade-SAS/OCCT Ā· GitHub