Reference
CatalogItem2xListingControl Class
CatalogItem2xListingControl Members
Type: RepeatDirection
A RepeatDirection value that specifies the direction to display sorted items by within the grid.
Supported values: "Horizontal" or "Vertical". Vertical displays items sorted in a top/down direction by column. Horzontal displays items sorted left to right by row.
The default value is "Vertical".