About categories
You can create categories to group your contacts, tasks, and memos. You can also narrow the contacts, tasks, and memos
that appear based on categories.
Category names are not case sensitive. More than one category can apply to a contact, task, or memo. If you use IBM Lotus
Notes, you can apply more than one category to a task on your BlackBerry smartphone, but only one category synchronizes
with the task in Lotus Notes.
User Guide
Contacts
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Categories are shared between the contact list, the task list, and the memo list and changes that you make in one
application are made in all applications.