Required attributes:
id unique value that identifies the group.
title text displayed in the group's header.
Optional attributes:
expand flag that determines whether the group can be expanded (type Y or N). The option equals 'N' by default.
cond condition that controls when the group is visible. There must be item id on the left side of = sign and a value on the right. When it is missing then the group is always visible. Use this option if you want to render a group conditionally based on a value of a select box item.
Required attributes when expand='Y'
allow_empty Expandable groups can be extended by clicking on 'add' or 'duplicate' links in their header and added copies of groups can be removed by clicking on 'remove' link. If you set allow_empty='N' then at least one group must always exist. Setting this option to 'Y' allows you to remove all copies of the group.