ReadListBegin is used by other methods that iterate through a list of items to ensure that the type about to be read is a list. ReadListBegin is also used by component writers in defined property ReadData methods. 

If the next item in the stream is not a start-of list marker as written by the WriteListBegin method, ReadListBegin raises an EReadError exception. 

A call to ReadListBegin is generally followed by a reading loop that terminates when the EndOfList method returns true, indicating that an end-of-list marker is next on the stream, at which point a call to ReadListEnd is required. 

EndOfList 

EReadError 

ReadListEnd 

WriteListBegin