-There are streams which do not have size by definition, such as socket streams.
-In that cases, GetSize returns an invalid size represented by
+Returns true if the streams supports seeking to arbitrary offsets.
+
+
+\membersection{wxStreamBase::OnSysRead}\label{wxstreambaseonsysread}
+
+\func{size\_t}{OnSysRead}{\param{void*}{ buffer}, \param{size\_t}{ bufsize}}
+
+Internal function. It is called when the stream wants to read data of the
+specified size. It should return the size that was actually read.
+
+
+\membersection{wxStreamBase::OnSysSeek}\label{wxstreambaseonsysseek}
+
+\func{off\_t}{OnSysSeek}{\param{off\_t}{ pos}, \param{wxSeekMode}{ mode}}
+
+Internal function. It is called when the stream needs to change the
+current position.
+
+
+\membersection{wxStreamBase::OnSysTell}\label{wxstreambaseonsystell}
+
+\constfunc{off\_t}{OnSysTell}{\void}