Modular content framework and document format methods and systems are described. The address generator calculates both an absolute value and a wrapped value and selects one in accordance with whether the wrapped value falls within the boundaries of the buffer. The EPS unit is also supported by the body frame. The image forming apparatus is characterized by further including a detection means for detecting density information of an image to be formed by the image forming means and a control means for variably changing a heat generating rate of the fixing apparatus depending on the image density information detected by the detection means. The facility data link channel is employed to transport packetized configuration and status information between the indoor carrier service unit and the span-powered T1 radio. The porous membrane is configured so that a fluid introduced into an open end of the tubular member will flow through side walls of the tubular member at a substantially uniform rate along a length of the tubular member.