epp(enhanced parallel port，增强形平行接口)
ipp(internet printing protocol，因特网打印协议)
ppm(paper per minute，页/分)
spp(standard parallel port，标准并行口)
tet(text enhanced technology，文本增强技术)
usbdcdpd(universal serial bus device class definition for printing devices，打印设备的通用串行总线级标准)
vd(variable dot，变点式列印)
twain(toolkit without an interesting name)协议
adsl: asymmetric digital subscriber line，不对称数字订阅线路
ah: authentication header，鉴定文件头
