The Page Rotation attribute is a metadata feature that is unique to PDF documents. It is often abbreviated as "page Rot."
The meta-information is pretty simple to understand. It indicates what direction and how pages within a pdf document are rotated. Particularly for merged documents or when PDF documents consist of both portrait and landscape page layouts, this data can be extremely valuable.
The value that is found in Page Rotation is typically one of three numbers:
These numbers define the amount of rotation used to create the webpage. The degree is usually indicated for the clockwise motion. This means that the rotation begins at the top and moves towards the left.
In some instances, counterclockwise rotation can occur too. This is usually stated as -90deg, instead of simple 90deg.