Merge parameters are special data references. They do not have a data source because they are defined as properties of the merge project. When a merge starts, variaDoc will set them based on the data you pass in through the command line, the web request or interactively. Their value is fixed for the duration of the merge unless their "Modifiable" setting is checked. You can use merge parameters in any expression, anywhere in the project. Refer to the chapter Working with variaDoc for more information on merge parameters.
Merge parameters do not have a data source, so they can simply be referenced by their name. For example, a merge parameter called orderid is used as follows:
Your order ID: $[orderid]
Merge parameters can also use inline formatting like this:
Your order ID: $[orderid|Lower]