Measurement Data Interchange Format (MDIF) files are typically used to store a collection of s-parameter files that are then controlled by variables to select which s-parameter file to use in simulation.
When you place an MDIF file on a schematic, the variables in the file will display on variables on the SUBCKT element as shown below with the variable called "Name" in this case.
When you edit the variable, it is an enumerated list of the variable values in the file.
In this case, there are variables named "1", "10", "100", "2" and "20". Notice the sorting of the variable values in this MDIF file. How these values are displayed is controlled by MDIF sorting options. To see these options, double-click on the Data Files node of the project tree and click on the MDIF Files tab of the dialog box.
This will be the default setting for all MDIF files in your project. You can also override this default per MDIF file from the options on the MDIF file (from the project tree, select the MDIF file, right click and select Options)
For example, if the same MDIF file's sort was set to Alphanumeric, the file will sort as shown below.