Global attributes allow a store admin to add particular product properties storewide. Hence, a store administrator can use global attributes to assign some common properties to all products in the store. Unlike product-specific and product class attributes, global attributes allow a store admin to set hidden attributes for products that can be used for internal store management purposes. Hidden global attributes are visible only to the store admin.
Global attributes can be added manually on a per-product basis or imported and assigned to multiple or all products in the store at once.
Generally, global attributes are viewed and managed via the Classes & Attributes -page of the Admin area:
X-Cart 5.4.x - Catalog -> Classes & Attributes
NOTE: In X-Cart 5.4.x, click the Edit attributes (N) link to access the global attributes listing page.
X-Cart 5.5.x - Catalog > Classes & Attributes > All Attributes
However, if necessary, it's also possible to create and manage global attributes (except hidden global attributes) via the "Attributes -> Global" tab of any product details page.