You can select to highlight parameters declared as type inout with an additional user-defined prefix or suffix. On the Objects page of the Options dialog (select the Tools | Options | Objects menu option), the Feature reference indicator panel enables you to set whether references are highlighted or not.

If you select the Highlight References checkbox, you can also indicate whether a prefix or suffix should be used, and the actual reference character to use. In the example above, the & character has been set as a prefix.

When you declare a parameter of type inout, it is assumed you are passing the parameter by reference rather than by value. If you have elected to highlight references, then this is displayed in the Diagram View.

The example below shows that the parameter strName is a string reference, and is highlighted using the chosen character and position.