How to correctly script the "OR" function in Group Filter section in Data Model in OBIEE?

Summary

In OBIEE, an error was prompted when I was scripting the "OR" function in Group Filter section of the Data Model interface.

Content

Hello Oracle community,

In OBIEE, an error was prompted when I was scripting the "OR" function in the Group Filter section of the Data Model interface. 

Please see attached screenshot for the two attempted scripts (also listed below), and their respective error messages.
1) G_1.ITEM_NUMBER == ABC OR DEF
2) G_1.ITEM_NUMBER == ABC OR G_1.ITEM_NUMBER ==DEF

The intend of the script is to have the data model to only produce records for specified items, using their item number (i.e. ABC, DEF).  For clarification, the entries are coded with alphabets albeit the column/attribute title spells "ITEM_NUMBER".  So far I only got to filter on a single item using the script below, which works: