Multi-Value custom fields are a new custom field type which allows you to store a delimited list of values in a single custom field. This is then parsed out and made available to become individual facet values when using this field as a facet.
There is a new “Multi-Text” Field type when creating custom field. To locate this option, click on "Utilities," then "Custom Fields." Click on the "+" icon at the top right, and you'll get this module that will pop up. Make sure you have "Multi Text" under the "Field Type" option.
You can now find the custom field for the facets under your product. Simply click on a product, open it and then click on the "Custom Fields" tab. When editing a product with a multi-text custom field it will show up as a text area.
You add one value per line and don’t need any delimited such as a comma or pipe.
You can also import and multi-text custom field values. They are treated as regular custom fields and each one is delimited by the pipe “|”.
When you add a multi-text custom field as a facet, Miva will automatically split it out into its individual values which allow you to filter on each value.