Cisco Cisco Unified IP Interactive Voice Response (IVR) 8.0(1) Leaflet

describes the properties of the Filter tab of the Explicit Confirmation 

customizer window.

Use the Extended Get Digit String step to capture either spoken or DTMF entries 
based on information defined at run time. If you are using ASR, digits can be 
spoken in the particular language of the call.

This step waits for input until the caller does one of the following:

Presses the terminating key (DTMF only)

Exhausts the maximum number of retries

Enters the maximum number of keys (DTMF only)

Does not respond before the timeout length is reached

When any previous escalating prompt in the script enters the Extended Get Digit 
String step, it is reset to the first prompt in its list.

The Extended Get Digit String step behaves exactly like the Get Digit String step, 
with two exceptions. First, with the Extended Get Digit String step, you can enter 
a Boolean expression for the Interruptible and Clear DTMF Buffer on Retry 
fields. Second, although the same limits apply to both steps, most of the Extended 
Get Digit String properties can be defined using variables or grammar expressions 
that can be changed while the script is running. 

Grammar

Variable or expression indicating the optional 
grammar expression to be used for recognizing 
Yes or No. 

If supplied, the grammar will override the system 
default grammar.