By default, the AllowVariables property is "=" ( equal character ), which indicates that a line can be divided in parts as var = expression, which indicates defining the var variable. The AddWildFormat method formats the line based on the giving wild characters expression. By default, the control has already the wild format defined as "<i>*=*</i>", which draws in italics any line that includes the = (equal) character ( define the variables ).  If the AllowVariables property is "", the control does not support defining any variable. The Variable property indicates the value of the specified variable. By default, the control supports variables such as Total and Count, which defines the Total of all valid lines, and count of them. The CalcType property specifies the type of operations the control supports.

By default, the control supports the following aggregate functions:

• AllowTotal property defines the Total keyword. The Total keyword, specifies the sum of all lines that are not empty, valid and defines no variables.
• AllowSubTotal property defines the SubTotal keyword. The SubTotal keyword, specifies the sum of all previously lines that are not empty, valid, defines no variables until another SubTotal keyword is found.
• AllowCount property defines the Count keyword. The Count keyword, counts all lines that are not empty, valid and defines no variables.
• AllowSubCount property defines the SubCount keyword. The SubCount keyword, counts all previously lines that are not empty, valid, defines no variables until another SubCount keyword is found.

 The following screen shot defines a few variables: