The article describe how to make term (ex: post tag) metabox a checkbox list rather than name input. So terms can be selected as like categories. This does work with Custom Taxonomies too. Non hierarchical taxonomy are those who doesn’t support parent or children.
Checkbox could be useful if the post tag or the custom taxonomy terms are less in numbers similar to categories.
Article written at hughlashbrooke.com and written by Hugh Lashbrooke.