Abstract: An engaging portion 30 is provided which is engageable with a portion-to-be-engaged 11b a displaceable integrally with a developer receiving portion 11 with a mounting operation of a developer supply container 1 to displace 11 in an upward direction U to bring a receiving opening into communication with a discharge opening. An engaging portion 30 includes a first engagement surface 31a extending in the upward direction U as going toward a developer accommodating portion of the developer supply container 1, and a second engagement surface 32a provided at a position closer to the developer accommodating portion than the first engagement surface 31a. When the receiving opening in communication with a shutter opening, a height of an end of the first engagement surface 31a close to the developer accommodating portion is higher than the second engagement surface 32a.

Abstract: In a data compression method using dictionaries, there are adopted a dynamic dictionary and a static dictionary to prevent the deterioration in the data compression ratio in the leading portion of the input data which cannot be efficiently compressed using the dynamic dictionary. Moreover, the configuration removes the disadvantage of the deterioration in the data compression ratio because character strings having a low appearance frequency occupy a large portion of the dictionary. Data to be compressed is inputted via an input unit to be decomposed into input bit strings 202. Using the input bit string as a retrieval key, a bit string retrieval is conducted through the static dictionary by a decision unit and a reference unit.