Annotations inside of PDFs are split into 2 groups: markup annotations and non-markup annotations.
Markup annotations are primarily used to mark up the content of a PDF document.
Non-markup annotations are used for other purposes, including interactive forms and multimedia.
There are 2 primary types of annotations, Markup and Non-Markup, as well as various subtypes.
Many annotation types are defined as markup annotations because they are used primarily to mark up PDF documents. These annotations have text that appears as part of the annotation and may be displayed in other ways by a viewer application, such as in a comments pane.
Each column within the Annotation Redaction Tool can be filtered using the button.
Markup annotations
Markup annotations can be separated into 3 main types:
Free text annotations: Text is displayed directly on the page.
Pop-up associated markup annotations: these include Text, Line, Square, Circle, Highlight, Underline, Strikeout, RubberStamp, Caret, Ink, and File Attachments.
Text Markup annotations are a subtype of pop-up associated annotations and contain one or more words in a document upon which the pop-up is associated with. They also include markup annotations such as Underline, Strikeout, Caret, Squiggly, etc..
Not all pop-up associated annotations are text markup annotations.
Sounds annotations: do not have a pop-up window but may have associated text specified by the Contents entry.
Types of Markup Annotations
Caret
CommonFigure
FileAttachment
FreeText
Ink
Line
Poly
Sound
Stamp
Text
Highlight
Squiggly
Strikeout
Underline
Non-markup annotations
What to know
Pop-up annotations typically do not appear by themselves and have a parent property which is associated to a markup annotation.
If no parent association is defined for Popup annotation, the viewer application may use the Popup's Contents as the text for the annotation.
Types of Non-Markup Annotations
Link
Movie
PDF3D
Popup
Redaction
RichMedia
Screen
Watermark
Widget
How to do it
Open the Blackout Document Review Tool by clicking the button at the bottom left of the viewer.
Choose the Annotation Redaction Tool by clicking the button.
Navigate to the annotation that will be redacted. Then, click the button. After a brief delay, the annotation will be redacted and the 'Redact' button will be grayed out and replaced with the button.
If the redaction needs to be undone, the button can be selected. This will undo the redaction of the selected annotation.
What else to consider
Redacting annotations manually
Annotations visible on the document (typically only markup annotations) can be redacted by placing a manual redaction on top of them.
Any redaction which overlaps with an annotation will remove it completely.
The ability to partially remove an annotation is not available.
PDF document review pane
All of the annotations are also listed in the pane below the document, known as the Blackout Document Review Pane.
From here, you will be able to filter on content, apply redactions to each annotation individually, or redact them all using the "redact all" button within that pane.
Annotations that are redacted will be removed completely from the document. There is currently no ability to remove only selected text.
Even though the annotation will be marked as redacted, it will not actually be removed from the Relativity document viewer due to a limitation in the Relativity viewer which does not give Blackout the ability to remove those annotations from the list.
To see the document with the annotation removed, the user would need to click the 'Download Marked Up File's button or run the document through the Production Preparation project.
button.
button at the bottom left of the viewer.
button.
button. After a brief delay, the annotation will be redacted and the 'Redact' button will be grayed out and replaced with the 
button.