## 5.7. Command Language File Rules

The following rules apply when using a text editor to change a CFX Command Language file:

- Changing the solution units outside of CFX-Pre is not recommended. For details, see Setting the Solution Units in the CFX-Pre User's Guide.

- Everything apart from expert parameter names is case-sensitive. Use care to distinguish upper case letters from lowercase letters. You should use lowercase letters for expert parameter names to match those shown in the Command File Editor Help's Expert Parameters section.

- The name of any variable must start with a letter (not a number or symbol). Subsequent characters can be letters, numbers, spaces, or tabs.

- Spaces appearing before or after a name are not considered to be part of the name.

- Multiple spaces and tabs appearing inside a name are treated as a single space.

- Nothing is sensitive to indentation. Indentation is used only to make the appearance of the text clearer.

- The comment character is the pound, or number sign (`#`). Anything appearing to the right of this character is ignored. For instance:

      PARAMETER = 3.2   # This text is ignored

- The line continuation character is the backslash (`\`). To break a long line of text into two or more lines, insert a backslash character at the end of the first line. For instance, both of the following declarations are handled the same way:

      NAME = default temperature used in the first simulation
      NAME = default temperature used \
             in the first simulation

- A line containing CFX Expression Language must be no more than 256 characters long. Other lines can be of any length.

The `RULES` and `VARIABLES` files can be a useful guide when editing a CCL file. For details, see RULES and VARIABLES Files.

Some objects in the CCL file can be defined with a default value and then overridden by local values. For example, the `SOLVER CONTROL` section of a CCL file may look like:

    SOLVER CONTROL :
       CONVERGENCE CONTROL :
          Maximum Number of Iterations = 100
          Timescale Control = Physical Timescale
          Physical Timescale = 5.E-1 [s]
       END
       EQUATION CLASS : momentum
          CONVERGENCE CONTROL :
             Timescale Control = Physical Timescale
             Physical Timescale = 1.E-1 [s]
          END
       END
       CONVERGENCE CRITERIA :
          Residual Type = RMS
          Residual Target = 1.E-4
       END
       ADVECTION SCHEME :
          Option = Upwind
          END
       DYNAMIC MODEL CONTROL :
          Global Dynamic Model Control = No
       END
    END

The first `CONVERGENCE CONTROL` object defines values that apply to all equation classes. The physical time scale is then locally overridden for the momentum equation class. Other objects, including the `ADVECTION SCHEME`, can be locally overridden in the same way. The order in which objects appear is not important, so an object can be assigned an override before its default has been set. Only some parameters may be set to a different local value; for example, it does not make sense to set the `Maximum Number of Iterations` locally.

Release 18.2 - © ANSYS, Inc. All rights reserved.