Annotation requests and responses transfer data within an EV_AttrValue structure. This structure is capable of storing a (nested) list of values of various data types.

Data can be placed into, and retrieved from, the EV_AttrValue using the following functions:

• EV_extractElement() extracts data from an EV_AttrValue
• EV_parseFormattedValue() constructs an EV_AttrValue containing the given data

There is also an API used for deleting values in an EV_AttrValue:

• EV_deleteValue() de-allocate memory associated with a value from an EV_AttrValue