PURPOSE: To provide a hardware filter for control of detectability, emphasis display, and invisibility of graphic primitives.
CONSTITUTION: Each of three display attributes is related to six counters in total of inclusive and exclusive counters 502 to 512. A flag indicating whether each class is a member of a set which is active at present or not and a 6-bit string indicating effects of the class to six filters are related to each class name. If there is a class name addition instruction and the flag is not set at the time of traversing a structure hierarchy, the flag is set, and a corresponding filter counter uses the 6-bit string to gate an increment signal. If there is a class name deletion instruction and the flag is not reset, the flag is reset, and the corresponding filter counter uses the 6-bit string to gate a decrement signal.
JIEEMUZU ARAN HAASUTATSUDO
DEBITSUDO KONRATSUDO TANNENBAU
