Assembly Design > Using Assembly > Working with Assemblies > About Showing Dimensions in Part and Assembly
  
About Showing Dimensions in Part and Assembly
When you create relations in Part and Assembly, click a component in the graphics window to display dimensions. The dimensions display in symbolic format. Click in the Relations dialog box or click Tools > Switch Symbols to display the value of the dimension. Click the symbolic dimension to enter it in the relation.
The terms session ID, runtime ID, coding symbol, and component ID are all equivalent.