Minimal Export

When creating (implementing) a STEP file from scratch, you don't need to include every possible entity from the start.

1. Shortest Path to Success

1. Prepare the HEADER Section: Specify the correct AP name.
2. Minimal PRODUCT Configuration:
   • PRODUCT
   • PRODUCT_DEFINITION
   • PRODUCT_DEFINITION_SHAPE
3. Geometry Basics:
   • CARTESIAN_POINT
   • DIRECTION
   • AXIS2_PLACEMENT_3D

2. Minimal Template (AP242)

Use this as a base and add geometric elements as needed. See the sample file (minimal_part.step) for reference.

ISO-10303-21;
HEADER;
FILE_DESCRIPTION(('Minimal Export Template'),'21;1');
FILE_NAME('export.step','2025-12-19T10:00:00',('Author'),('Organization'),'Processor','System','');
FILE_SCHEMA(('AP242_MANAGED_MODEL_BASED_3D_ENGINEERING_MIM_LF { 1 0 10303 442 1 1 4 }'));
ENDSEC;
DATA;
#10 = PRODUCT('PART_ID','PART_NAME','',(#20));
#20 = PRODUCT_CONTEXT('',#30,'mechanical');
#30 = APPLICATION_CONTEXT('managed model based 3d engineering');
#40 = PRODUCT_DEFINITION_FORMATION('1','',#10);
#50 = PRODUCT_DEFINITION('design','',#40,#60);
#60 = PRODUCT_DEFINITION_CONTEXT('part definition',#30,'design');
#70 = PRODUCT_DEFINITION_SHAPE('','',#50);
#80 = SHAPE_DEFINITION_REPRESENTATION(#70,#90);
#90 = SHAPE_REPRESENTATION('',(#100),#110);
#100 = AXIS2_PLACEMENT_3D('',#120,#130,#140);
#110 = ( GEOMETRIC_REPRESENTATION_CONTEXT(3) 
         GLOBAL_UNCERTAINTY_ASSIGNED_CONTEXT((#150))
         GLOBAL_UNIT_ASSIGNED_CONTEXT((#160,#170,#180))
         REPRESENTATION_CONTEXT('Context #1','3D Context') );
#120 = CARTESIAN_POINT('',(0.0,0.0,0.0));
#130 = DIRECTION('',(0.0,0.0,1.0));
#140 = DIRECTION('',(1.0,0.0,0.0));
#150 = UNCERTAINTY_MEASURE_WITH_UNIT(LENGTH_MEASURE(1.0E-06),#160,'DISTANCE_ACCURACY_VALUE','');
#160 = ( LENGTH_UNIT() NAMED_UNIT(*) SI_UNIT(.MILLI.,.METRE.) );
#170 = ( NAMED_UNIT(*) PLANE_ANGLE_UNIT() SI_UNIT($,.RADIAN.) );
#180 = ( NAMED_UNIT(*) SI_UNIT($,.STERADIAN.) SOLID_ANGLE_UNIT() );
ENDSEC;
END-ISO-10303-21;

3. Implementation Checklist

• [ ] Instance ID Consistency: Ensure #numbers are unique within the file.
• [ ] HEADER AP Name: Is the FILE_SCHEMA correct? (Did you mix up AP214 and AP242?)
• [ ] Unit System (SI_UNIT): Explicitly state whether you are using .MILLI.,.METRE. (mm) or .METRE. (m).
• [ ] Structure Integrity: Are ENDSEC; and END-ISO-10303-21; present?

4. Geometry Verification Tips

• Using ADVANCED_BREP_SHAPE_REPRESENTATION is the most reliable method.
• Start with a single CLOSED_SHELL.

5. Validation Tools

• NIST STEP File Analyzer: A powerful tool to check if generated files comply with the standard.
• CAx-IF Checkers: Validate files from an interoperability perspective.

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📚 Next Steps

• Common Pitfalls - Points where implementations often fail.

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