Enterprise Forms has a mechanism called Conditional evaluation in which a number of powerful features derive from. 

• Conditional Databind: the ability to bind data to form fields based on a condition
• Conditional Visibility: the ability to hide/show as well as enable disable form fields based on a condition
• Conditional Workflow: the ability to move a form to different workflow states based on a certain condition
• Conditional Processing Task: the ability to execute advanced workflow processing task based on a certain condition.

Conditional evaluation engine provides a set of operators that could be used in an expression.  The list below describes in details the purpose of each conditional operator

Conditional Operator	Data Type	Detailed Description
Any value	String	Always return true to the selected condition.
Equals	String	Returns true if the selected field value match exacly to the provided value.  The match is case sensitive.
Not Equals	String	Returns true if the selected field value is Not Equals to the provided value.  The match is case sensitive.
Less Than	Numeric  or Date	Returns true if the selected field value is Less Than the provided value.  The evaluation is only applicable to numeric and date type values.
Less Than Or Equals	Numeric or Date	Returns true if the selected field value is Less Than or Equals To the provided value.  The evaluation is only applicable to numeric and date type values.
Greater Than	Numeric or Date	Returns true if the selected field value is Greater Than the provided value.  The evaluation is only applicable to numeric and date type values.
Greater Than or Equals	Numeric or Date	Returns true if the selected field value is Greater Than or Equals To the provided value.  The evaluation is only applicable to numeric and date type values.
Contains	String	Returns true if the selected field value Contains a provided value.
Empty or Equals	String	Returns true if the selected field value Contains a provided value or is empty.
Empty or Not Equals	String	Returns true if the selected field value is Empty or Not Equals to the provided value.
Empty or Contains	String	Returns true if the selected field value is Empty or Equals to the provided value.
Not Contains	String	Returns true if the field value does Not Contain the provided value
Empty or Not Contains	String	Returns true if the field value is Empty or does Not Contains the provided value.
In List	String	Returns true if the field value is contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|)
Not In List	String	Returns true if the field value is Not contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|)
State In List	State Id or State Name	Returns true if the Current Workflow State is contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|).  The List can contain a combination of State Id or State Name.
State Not In List	State Id or State Name	Returns true if the Current Workflow State is Not contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|).  The List can contain a combination of State Id or State Name.
DNN Role In List	Role Id or Role Name	Returns true if one of the associated DNN Roles of the current logged on user is contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|).  The List can contain a combination of Role Id or Role Name.
DNN Role Not In List	Role Id or Role Name	Returns true if one of the associated DNN Roles of the current logged on user is Not contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|).  The List can contain a combination of Role Id or Role Name.
Custom Role In List	Custom Form Role Id or Custom Form Role Name	Returns true if one of the associated Custom Form Roles of the current logged on user is contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|).  The List can contain a combination of Role Id or Role Name.
Custom Role Not In List	Custom Form Role Id or Custom Form Role Name	Returns true if one of the associated Custom Form Roles of the current logged on user is contained In the List in the provided value.  The list must be separated by a coma (,), semi-colon (;) or pipe (|).  The List can contain a combination of Custom Form Role Id or Custom Form Role Name.