Model-Based Definition > Geometric Dimensioning and Tolerancing Advisor > Advisor Message Help > Part Messages > System of Units Not Compatible with Tolerancing Standard
  
System of Units Not Compatible with Tolerancing Standard
The part model has length units that are not compatible with the ISO tolerancing standard. ISO 129-1, which is automatically invoked by ISO 1101:2012, states that SI units shall be used for dimensions (see ISO 1000 for more information about the SI system of units). You should either select an SI length unit (e.g., mm, cm, or m) for the model or you should select a different tolerancing standard.