XMP is what you're looking for, now an ISO standard it is no longer vendor specific to Adobe.
XMP files are where Adobe Camera Raw stores its data on crop and rotation options for example. Plus, XMP is usually implemented as a 'sidecar' file so absolutely no changes to the source file are made, allowing for unlimited changes without loss of data.
The 'standard' metadata systems like EXIF & IPTC do not store that information (so far as I'm aware.)
CropAngle are some of the properties are used by Adobe Camera Raw Settings to store crop information and can be found in the namespace
http://ns.adobe.com/camera-raw-settings/1.0 (usually mapped to