From the SW 2013 Help File:

Global Variables in Configurations

You can configure global variables.

In a design table, the column header for controlling the value of a global variable uses this syntax:

\$VALUE@global_variable_name@EQUATIONS

The column header is not case sensitive.

Following these instructions while using \$VALUE@OD1@EQUATIONS results in the following error:

"Column Heading ''\$VALUE@OD1@EQUATIONS'' contains and invalid feature name ''EQUATIONS''

This is on a very simple part. The variable are defined, so equations should be a valid object as it shows up in the design tree.