code: protected int getSize()
     {
        if (tc.isEntryEnabled()) SibTr.entry(this, tc, "getSize");
        int headerSize = 0;
        if (layout == JFapChannelConstants.XMIT_PRIMARY_ONLY)
           headerSize = JFapChannelConstants.SIZEOF_PRIMARY_HEADER;
        else if (layout == JFapChannelConstants.XMIT_CONVERSATION)
           headerSize = JFapChannelConstants.SIZEOF_PRIMARY_HEADER + JFapChannelConstants.SIZEOF_CONVERSATION_HEADER;
        else if (layout == JFapChannelConstants.XMIT_SEGMENT_START)
           headerSize = JFapChannelConstants.SIZEOF_PRIMARY_HEADER + JFapChannelConstants.SIZEOF_CONVERSATION_HEADER + JFapChannelConstants.SIZEOF_SEGMENT_START_HEADER;
        else if (layout == JFapChannelConstants.XMIT_SEGMENT_MIDDLE)
           headerSize = JFapChannelConstants.SIZEOF_PRIMARY_HEADER + JFapChannelConstants.SIZEOF_CONVERSATION_HEADER;
        else if (layout == JFapChannelConstants.XMIT_SEGMENT_END)
           headerSize = JFapChannelConstants.SIZEOF_PRIMARY_HEADER + JFapChannelConstants.SIZEOF_CONVERSATION_HEADER;
        else
        {
           throw new SIErrorException(TraceNLS.getFormattedMessage(JFapChannelConstants.MSG_BUNDLE, "TRANSDATA_INTERNAL_SICJ0060", null, "TRANSDATA_INTERNAL_SICJ0060")); // D226223 
        }
        int retValue = primaryHeaderFields.segmentLength - headerSize;
        if (tc.isEntryEnabled()) SibTr.exit(this, tc, "getSize", ""+retValue);
        return retValue;
     }
docs: Returns the size of the data associated with this transmission
  (in bytes)
  @return Returns the size of the data associated with this transmission