About Units in Relations
By default, relations are unit-sensitive. Unit-sensitive relations behave as follows:
• If you mix parameters with different units in a relation, the system converts them in order to solve a relation. For example, if the system units are mm, and you have a parameter B with the value of 1 inch, the relation d1=B is evaluated as d1=25.4mm.
• You can mix unitless parameters and parameters with units in the same relation. For example, if you have a unitless parameter A and parameter B with units, you can have a relation: d3=B*A. In this case, A is used as a scalar value. You can also include a unitless parameter and specify units directly in the relation. For example, d3=A[mm] + B.
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Creo versions available before Creo 1.0 were not unit sensitive.
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Checking for Units in Relations
You can set the configuration option relations_units_sensitiveto check for units when solving relations. This option has the following values:
• yes (default)—Solve relations taking units into account. If units are missing, the system issues a warning.
• no—Ignore units in relations.
You can control whether relations for the selected object (listed in the Relations editor) are unit-sensitive by clicking 
or clicking > in the Relations dialog box.
or clicking > in the Relations dialog box.| | You can set the relations_units_sensitive configuration option to no, and then apply Unit Sensitive. This prevents the system from issuing error messages if units are missing. |
The Verify command checks for validity of relations from the relations perspective and issues and error if units are contradictory. You can set the configuration option relations_num_const_units to issue a warning if units are missing in a relation. If the option is set to yes, the system checks for units, issues a warning, and prompts you to fix the relation by applying units.
| | • If you want to add a relation to nonsolid models, for example, bulks, you must always specify units for numeric constants. • The setting of the relations_num_const_units configuration option is ignored for nonsolid models. |