When opening your equations dialog in a part created in Solidworks 2015 or later, you may notice a yellow warning icon next to some of your equations. When the cursor is moved over the warning icon, the message 'Relation defined out of context' appears.
This occurs when a part that depends on assembly equations or dimensions is opened in a separate window from the assembly. An example of a dependent situation is if you were to equate the length of a sketch dimension of one part to the depth of an extrusion of another part in the same assembly.
This error message does not mean the equation is broken. The equation is still valid in the context of the assembly. Solidworks displays this warning message because in general, it is not a good modeling practice to have the assembly equations drive the part. If you insert the part into a different assembly that does not have equations, you might experience other problems.
If you would like to edit the equation, it must be done in the context of the assembly. To edit in the context of the assembly, first open the assembly that the part is referencing. Right click on the part in the feature manager tree or the graphics area and select "edit part. Expand the part in the feature manager tree and right click on the equations folder. Select "manage equations".
The warning dialog does not appear now that the equations are opened in the context of the assembly. Valid equations can be edited and updated successfully.