<FilterDescriptor Type = "String" FilterField = "String" Name = "String" DefaultDisplayName = "String" IsCached = "Boolean"> </FilterDescriptor>
Elements and attributes
The following sections describe attributes, child elements, and parent elements.
Attributes
Attribute
Description
**Type**
Required.
The type of the filter descriptor.
The following table lists the possible values for this attribute.
Value
Description
Limit
Used while querying an external system and the value of which can be interpreted as a limit on the number of external items (**EntityInstances**) that are returned when the method that it belongs to is called.
PageNumber
Wildcard
Used while querying an external system. Its value represents a pattern of regular and wildcard characters that is matched against the value of a particular field of the set of EntityInstances. The external system returns only those EntityInstances whose field values match the specified pattern.
UserContext
Used while querying an external system. Its value can be set automatically by any client application to the identity of the user who is calling the external system. This value can then be used by the external system to authorize and then filter the results returned.
UserCulture
Username
Password
LastId
SsoTicket
UserProfile
Used while querying an external system. Its value can be obtained by examining the current user's profile. The external system can use its value to filter the results returned.
Comparison
Used while querying an external system. An external system can compare a **ComparisonFilter** value with the value of a particular field of a set of **EntityInstances** and only those **EntityInstances** where the field values pass the comparison test can be returned.
Timestamp
Input
Used while calling an operation in an external system. An external system can use the value of an **InputFilter** as additional arguments for the operation.
Output
Used while calling an operation in an external system. Additional results of an operation that cannot be captured by **ReturnTypeDescriptor** can be retrieved as a value of the **InputOutputFilter**.
InputOutput
Used while calling an operation in an external system. An external system can use the value of an **InputOutputFilter** as additional arguments for the operation, and additional results of an operation that cannot be captured by **ReturnTypeDescriptor** can be retrieved as a value of the **InputOutputFilter**.
Batching
BatchingTermination
ActivityId
**ActivityId** is used when calling an operation on the external system. Its value is set to a GUID that represents the current operation context. If no such value is available, this filter generates a random GUID. On SharePoint Foundation 2010, this filter uses the **CorrelationID**.
**FilterField**
Optional.
Attribute type: **String**
**Name**
Required.
The name of the filter descriptor.
Attribute type: **String**
**DefaultDisplayName**
Optional.
The default display name of the filter descriptor.
Attribute type: **String**
**IsCached**
Optional.
Specifies whether this filter descriptor is used frequently. If set to **true**, Business Data Connectivity (BDC) service caches this filter descriptor in memory.