This is a local stream abstraction, and implementation, that allows the calling code to operate over final methods even when the original data source is an interface, such a Reader. When passed a users data buffer it simply operates of the entire buffer directly. When the input source is a stream is creates it's own local buffers, using UnifiedInputBufferX and UnifiedDataPageX. These allocate pages and loads them, a page at a time, from the stream using the highest bandwidth stream interface available. In this class the unread is only allowed to unread characters that it actually read. This is checked, when possible, when the local _debug is true. This is checked when the unread is bad into data that is present in the current buffer. When the unread crosses a buffer boundary the unread value is simply written into the space at the beginning of the block, which is reserved for that purpose. On all system allocated pages the user data starts at an offset in from the front of the buffer, The offset is set by UNREAD_LIMIT. This is not necessary at either the beginning of the input or for a user supplied buffer since the entire input is a single buffer.