Recently Oracle in their R12.1.3 release has by default enabled Look Ahead LOV feature which was introduced in R12.1.2.
First a brief intro about Look Ahead LOV:-
When an end-user types in characters in the LOV search field, the results are fetched and displayed inline to the LOV component.
A user can select a value from this look ahead window just as in the classic LOV window. For most use cases, this capability eliminates the need to launch the LOV modal window, to perform a search within the window, and to navigate through the results using Next / Previous links in the LOV window results table, thereby saving a number of clicks and server-side requests, and significantly enhancing end-user productivity.
So to implement the same feature in R12.1.2 so you can follow below steps:
First create a simple LOV
Now for Look Ahead we need to set the following properties of MessageLovInput field
1) Under Functional heading, set Look Ahead Enabled to True
2) Look Ahead Search to "Contains" or "Start With"
Contains means all the records which contains the characters entered by user.
Start with means all the records that start with characters entered by user.
3) Minimum Character for Search to Any Number as per your requirement.
These are the minimum number of characters required to initiate the Look Ahead LOV eg 1,2,3 or more
Finally the LOV will look like this when user enters any character.
Important Profile Options for Look Ahead LOVs
FND: Disable Look Ahead LOV : Determine whether the Look Ahead LOV feature is enabled or disabled at the site or Application level.
Valid values are: FALSE - Look Ahead LOV feature is enabled.
TRUE - Look Ahead LOV feature is disabled
Default Value.: FALSE at Site level.
FND: Minimum Characters for Look Ahead:
If the Look Ahead LOV feature is enabled,
then this profile determines the minimum
number of characters a user must enter to
activate the Look Ahead LOV window.
Default Value : 3 at Site level
Hope it helps. Do let us know your views or comments