When creating a sheet metal part it would be helpful if the parameter for thickness was named thickness and not a dimension name like d9 or d22. If you change the sheet metal rule, the dimension updates and anything you link to it will have to be relinked. This is worked around by creating your own "Thickness" and linking it to whatever the current rule is, but frustrating when changes are made to a rule, even if it uses the same thickness value as a previous rule.